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Police Body Armor Standards and Testing, Vol. I

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Title:
Police Body Armor Standards and Testing, Vol. I
Series Title:
Police Body Armor Standards and Testing
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United States. Congress. Office of Technology Assessment.
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U.S. Congress. Office of Technology Assessment
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Language:
English
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55 p. : ill. ; 28 cm.

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Subjects / Keywords:
Police -- United States -- Equipment and supplies -- Standards ( LCSH )
Police -- United States -- Protection ( LCSH )
Protective clothing -- Testing ( LCSH )
Armor -- United States -- Testing ( LCSH )
Genre:
federal government publication ( marcgt )

Notes

General Note:
This report discusses the standards for body-armor. The report describes the origin of the standard, the rationale for particular provisions, and the main points of controversy, which concern acceptable risks, the validity and discrimination of the test, and the reproducibility of results.

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University of North Texas
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University of North Texas
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This item is a work of the U.S. federal government and not subject to copyright pursuant to 17 U.S.C. §105.
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Y 3.T 22/2:2 P 75/2/ ( sudocs )

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IUF:
University of Florida
OTA:
Office of Technology Assessment

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Police Body Armor Standards and Testing, Vol. I August 1992 OTA-ISC-534 NTIS order #PB92-216100

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Recommended Citation: U.S. Congress, Office of Technology Assessment, Police Body Armor Standards and Testing: Volume I, OTA-ISC-534 (Washington, DC: U.S. Government Printing Office, August 1992). For sale by [he U.S. Government Printing Office Superintendent of Documents, Mail Stop: SSOP, Washington, DC 20402-9328 ISBN 0-16 -037987-3

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Foreword For two decades, the number of police officers shot to death each year has been declining while the number of officers shot has been increasing. The decrease in the lethality of shootings is partly attributable to the increase in wearing of bullet-resistant body armor, especially soft, inconspicuous armor designed to be worn full-time. A prospective purchaser can see how much of the body an armor garment covers but cannot see whether it will stop a particular kind of bullet at a particular velocity and protect the wearer from the impact. To provide benchmarks for protection, the National Institute of Justice issued NIJ Standard 0101.03 in 1987. It specifies standard procedures for testing samples of armor. If samples of a model pass, the NIJ or the manufacturer may certify that the model has the type of ballistic resistance for which it was tested. The standard has been controversial since it was issued. This Report describes the origin of the standard, the rationale for particular provisions, and the main points of controversy, which concern acceptable risks, the validity and disc rumination of the test, and the reproducibility of results. OTA finds that resolving these controversies will require specifying acceptable risks quantitatively, performing additional research to test validity, and implementing a quality-control program. To date, all armor of NIJ-certified models has performed as rated in service-but so has uncertified armor, including armor that would fail the test specified by the standard. This has provoked charges that the NIJ test is too stringent and fails to discrimin ate some safe armor from unsafe armor. The validity and discrimin ation of the test are technical issues that are susceptible to scientific analysis if the NIJ specifies maximum acceptable risks quantitatively. The Report describes illustrative specifications of acceptable risks and an experimental method for deciding whether the current test, or any proposed alternative, limits the risks as required. It also describes and compares several options for a quality-control program. This assessment was requested by Senator Joseph R. Biden, Jr. (Chairman), Senator Strom Thurmond (Ranking Minority Member), Senator Dennis DeConcini, and Senator Edward M. Kennedy of the Senate Committee on the Judiciary, Congressman John Joseph Moakley, Chairman of the House Rules Committee, and Congressman Edward F. Feighan of the House Committee on the Judiciary and of its Subcommittees on Crime and on Economic and Commercial Law. u JOHN H. GIBBONS Director iii

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Police Body Armor Standards and Testing Advisory Panel Lester B. Lave, Panel Chair James H. Higgins Professor of Economics Graduate School of Industrial Administration Carnegie-Mellon University George N. Austin, Jr. National Officer Fraternal Order of Police Lane Bishop Statistician Center for Applied Mathematics Allied-Signal, Inc. Alfred Blumstein Dean and J. Erik Jonsson Professor of Urban Systems and Operations Research School of Urban and Public Affairs Carnegie-Mellon University Michael Bowman Vice President and General Manager Fibers Department E.I. duPont de Nemours & Co., Inc. Milton Brand President The Brand Consulting Group James T. Curran Professor and Dean for Special Programs John Jay College of Criminal Justice City University of New York Donald R. Dunn President H.P. White Laboratory, Inc. Martin Fackler President International Wound Ballistics Association Michael A. Goldfarb General Surgeon Monmouth Medical Center David C. Hill President Fibers Division Engineered Materials Sector Allied-Signal, Inc. Max Henrion Member of the Technical Staff Rockwell International Science Center Alexander Jason Ballistics Consultant ANITE Group Harlin R. McEwen Chief Ithaca Police Department Isaac Papier Managing Engineer Burglary Detection and Signaling Dept. Underwriters Laboratories, Inc. Richard Stone President Point Blank Body Armor, Inc. Dieter Wachter Vice President of High-Performance Fabric Clark-Schwebel Fiberglass Corp. Robert Wantz President Personal Protective Armor Association NOTE: OTA appreciates and is grateful for the valuable assistance and thoughtful critiques provided by the advisory panel members. The panel does not, however, necessarily approve, disapprove, or endorse this report. OTA assumes full responsibility for the report and the accuracy of its contents. iv

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OTA Project StaffPolice Body Armor Standards and Testing Lionel S. Johns, Assistant Director, OTA Energy, Materials, and International Security Division Alan Shaw, International Security and Commerce Program Manager Michael B. Callaham, Project Director Brian McCue, Senior Analyst Jonathan Tucker, Analyst (through May 1991) Administrative Staff Jacqueline Robinson Boykin Office Administrator Louise Staley Administrative Secretary v

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Acknowledgements OTA gratefully acknowledges the assistance of the following individuals and organizations for their help in supplying information or in reviewing drafts of portions of this report. The individuals and organizations listed do not necessarily approve, disapprove, or endorse this report; OTA assumes full responsibility for the report and the accuracy of its contents. Allied-Signal, Inc. Kevin McCarter Sam White Steven A. Young Aspen Systems, Inc. Marc H. Caplan Wendy Howe Candace McIlhenny Canadian General Standards Board Marian L. Gaucher E.I. duPont de Nemours and Company, Inc. Thomas E. Bachner, Jr. William Brierly Louis H. Miner Helen A. Slavin Elgin (IL) Police Department Charles A. Gruber General Motors Research Laboratories David C. Viano Hartford (VT) Police Department Joseph G. Estey Home Office Police Scientific Development Branch Eric Brown Jaba Associates (Ontario) Alan Athey Point Blank Body Armor, Inc. Gaetan (Tom) J. Dragone Second Chance Body Armor, Inc. Clinton Davis Lisa Hinz Lester Shubin U.S. Department of Commerce National Institute of Standards and Technology Keith Eberhardt Lawrence K. Eliason Daniel E. Frank John Whidden Patent and Trademark Office Deborah L. Kyle U.S. Department of Defense Strategic Defense Initiative Organization Nicholas Montanarelli Department of the Army Ballistics Research Laboratory Russell N. Prather Chemical Research, Development, and Engineering Center Larry Sturdivan U.S. Department of Justice Bureau of Alcohol, Tobacco, and Firearms Daniel Hartnett Federal Bureau of Investigation Bunny Morris David Pisenti Charles Barry Smith National Institute of Justice Paul Cascarano Charles DeWitt Paul Estaver University of Maryland Girish Grover Ann Beth Jenkins Ian Twilley Frederick Peter Watkins vi

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INTRODUCTION . . . . . . . . . . . . . . . . . BACKGROUND . . . . . . . . . . . . . . . . . Soft Armor and Hard Armor . . . . . . . . . . . . . . S ummary of NIJ Standard 0101.03 . . . . . . . . . . . . . FINDINGS . . . . . . . . . . . . . . . . . . . Benefits of Wearing Armor . . . . . . . . . . . . . . Factors Influencing Wearing of Armor . . . . . . . . . . . . Goals obtesting and Certitfication . . . . . . . . . . . . . Test Procedures . . . . . . . . . . . . . . . . . Assuring Quality . . . . . . . . . . . . . . . . . UNRESOLVED ISSUES . . . . . . . . . . . . . . . OPTIONS FOR THE DEPARTMENT OF JUSTICE . . . . . . . . . Specify Acceptable Risks . . . . . . . . . . . . . . . Revise NIJ Standard 0101.03 . . . . . . . . . . . . . . Assure Quality . . . . . . . . . . . . . . . . . Sponsor Research . . . . . . . . . . . . . . . . OTHER POLICY OPTIONS . . . . . . . . . . . . . . . Expand FTC Activities; Involve OSHA . . . . . . . . . . . LEGISLATIVE OPTIONS . . . . . . . . . . . . . . . Fund NIJ-Sponsored Research . . . . . . . . . . . . . BIBLIOGRAPHY . . . . . . . . . . . . . . . . . 1 7 7 7 13 13 14 16 21 27 27 29 30 32 36 38 39 39 40 40 41 Boxes Box Page A. How Soft Armor Works . . . . . . . . . . . . . . . B. Kevlar R and Twaron R . . . . . . . . . . . . . . . C. Spectra R and Spectra Shield TM . . . . . . . . . . . . . . D. Trends in Weapons and Ammunition Used in Assaults on Police . . . . . . E. Types of Guns . . . . . . . . . . . . . . . . . F. ABCs of Ammunition, Bullets, and Cartridges . . . . . . . . . . G. Stringency, Validity, and Reproducibility. . . . . . . . . . . . H. Statistical Confidence . . . . . . . . . . . . . . . . 2 3 4 8 9 10 17 18 Figures Figure Page l. Certification That a Model of Armor Complies With the NIJ Standard is Based on Inspection and Testing of Samples Submitted by the Manufacturer . . . . . 13 2. Instrumented Ballistic Test Range for Testing Armor as Specified in NIJ Standard 0101.03 . . . . . . . . . . . . . . . 14 3. Sequence of Aim Points on Each Panel, as Specified in NIJ Standard 0101.03 . . 14 4. How Fatal Bullet Wounds in the Torso Would Decrease if the Wear Rate Increased . 14

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ContentsContinued Page 5. Wear Rate Versus Temperature-Humidity Index (THI) . . . . . . . . 15 6. Wear Rate Versus Month . . . . . . . . . . . . . . 15 7. Wear Rate Versus Areal Density of Armor . . . . . . . . . . . 16 8. Reenactment of a Ballistic Test That Armor Shot in an Assault Could Have Been Subjected To . . . . . . . . . . . . . . . . 22 9. Discrimin ation of the NIJ Test for Protection From the Impact of Stopped Bullets . 23 10. Shots Per Panel in Actual Assaults . . . . . . . . . . . . 24 11. Effect of Wetness on Ballistic Resistance of Kevlar R Armor . . . . . . 29 12. Estimates of V 50 and V 10 Obtained by Logistic Regression . . . . . . . 35 13. Notional Control Chart for Sequential Lot-Acceptance Testing . . . . . . 37 Tables Table Page 1. Types of Ballistic Resistance Defined by NIJ Standard 0101.03 in Terms of Bullets and Velocities Specified for Testing . . . . . . . . . . . 11 2. Tyes of Ballistic Resistance Defined by NIJ Standard 0101.03 in Terms of Guns and Ammunition Against Which Protection is Expected . . . . . . 12 3. Choices for Safety Goals . . . . . . . . . . . . . . . 32 viii

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Police Body Armor Standards and TestingExamples of Soft Armored Undergarments Silken body armor of the type Austrian Archduke Francis Ferdi-nand was reported to have worn on the day he was assassinatedby a shot in the neck in 1914.SOURCE: Bashford Dean, 1920. [53]INTRODUCTIONEvery year, about 60 sworn police officers are shot to death in the line of duty.l 2 At the same time, about 20 are saved by wearing armor. Had all the officers shot in recent years been wearing armor when shot, another 15 per year would likely have been saved from fatal gunshot wounds, roughly doubling the present number saved, and more than 15 others would likely have been saved from death by other causes.3Modern soft body armor containing layers of material made fromsynthetic fiber. This armor uses woven fabric; other soft armoruses sheets of nonwoven material made by bonding syntheticfibers with adhesive.SOURCE: Second Chance Body Armor, Inc., 1991.Most police officers serving large jurisdictionsreport they have armor and wear it at all times whenon duty and clearly identifiable as police officers[102]. The kind of armor usually worn is soft armor,which is designed to be concealable-most styles are undergarments-and comfortable enough to be worn routinely. Such armor is designed for protection from handgun bullets but not from rifle bullets or edged or pointed weapons such as knives or icepicks. The distinctive, nonconcealable tactical Most lethal shootings are felonious; a few are accidental. such as private

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2 Police Body Armor Standards and Testing: Volume 1 Box AHow Soft Armor Works Soft body armor works by catching the bulletin a net-like web of very strong fibers. The bullet stretches not only the few fibers it hits, but also others in contact with them, and many more that those pull. As in any net, the key to success is that many fibers, even those not actually touching the bullet, elongate in response to the collision and so absorb the energy of the bullet. Even so, materials available today do not permit the construction of a vest from a single ply of fabric-a number of layers, often about one or two dozen, are needed to stop a bullet. Soft armor has been made from a variety of natural and, more recently, synthetic fibers. For example, silk, which had been used for armor in medieval Japan, was used in American ballistic (bullet-resistant) armor late in the nineteenth century. It attracted Congressional attention after President William McKinley was assassinated in 1901, and was said to have been worn by Archduke Francis Ferdinand of Austria when he was killed by a shot in the head, which precipitated World War I. Although it provided some protection against handgun bullets at low velocity (e.g., .40-caliber lead or .45-caliber jacketed at 400 feet per second), it could not stop higher velocity handgun bullets (e.g., .45-caliber jacketed at 600 feet per second), much less rifle bullets. This shortcoming, together with the expense of silk (then about $80 per garment), made silk armor unattractive to the U.S. Ordnance Department in World War I. [53] The tensile-strength-to-weight ratio (tenacity) of silk-no more than about 5 grams per denier [89]was surpassed by synthetic fibers such as nylon (8 g/d) and, later, Kevlar R (26 g/d) and Spectra TM (35 g/d). Some spider silk has even greater tenacity, [162] but it cannot be cultivated and collected economically as silkworm silk can. Genetic engineers are striving to develop a way to copy it. During the Second World War and the conflict in Korea, the United States Army developed soft armor made of nylon. These vests provided considerable protection, but were very bulky. Concealable soft body armor as we know it today was made possible in the mid-1960s, when a solvent for polyaramid plastic was discovered; this permitted the production (sp inning) of polyaramid fiber (see box B). Polyaramid fibers have higher tenacity than nylon does, and less elongation before breaking than silk or nylon. The first soft body armor for police use, however, was of nylon. Richard C. Davis holds several patents relating to police body armor, [47, 48,49, 50] including one [47] for a small, light nylon vest designed to protect the wearers vital organs from the short-barreled, medium-caliber handguns known as Saturday night specials. The application for this patent was filed on May 8, 1972. Today, several types of polyaramid fiber are marketed under the names Kevlar R (by the duPont de Nemours Co., Inc.) and Twaron R (by Akzo, Inc.). The fiber is woven into fabric by weavers (two or three produce most of the U.S. ballistic fabric), and the fabric is used in the construction of vests by several U.S. and foreign manufacturers, The first save credited to Kevlar R armor occurred in 1973. More recently, soft armor has been made from fibers of extended-chain polyethylene (ECPE). Produced by Allied-Signal, Inc., the fiber, marketed as Spectra TM has greater tenacity and slightly less elongation than Kevlar TM Although some Spectra TM fiber is woven into Spectra TM fabric for armor, Spectra TM is also used by Allied-Signal in the manufacture of Spectra Shield R a nonwoven composite material used in soft as well as rigid armor (see box C). A single thin, flexible sheet of Spectra Shield R is made by (1) bonding a single layer of closely spaced parallel fibers together with Kraton TM resin (produced by Shell Chemical) to form a single ply, (2) bonding two such plies together, one rotated 90 degrees from the other, and (3) coating each surface of the two-ply sheet with a film to reduce friction and abrasion. Several such sheets are required to provide protection from handgun bullets: Spectra Shield R was first sold to body armor manufacturers in 1988. Some manufacturers make hybrid armor by sandwiching sheets of Spectra Shield R between layers of Spectra TM or Kevlar R fabric. Untreated fabric woven from either polyaramid or ECPE fiber loses some ballistic performance when it is wet. Possibly the water lubricates the intersections of the weave, so that stretching fibers slip on their neighbors rather than pulling them into sharing the work of stopping the bullet. There are three options for preventing or reducing this effect: l The fiber or fabric may be treated by any of several processes to promote water-repellency. Armor panels of untreated fabric may be encased in waterproof covers. l Armor panels may use enough untreated fabric to provide the ballistic resistance desired even when wet. Upon drying, untreated fabric of either type regains its original ballistic performance. The ballistic resistance of panels of Spectra Shield R non-woven composite material is unaffected by wetness. SOURCE: (Office of Technology Assessment, 1992.

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Police Body Armor Standards and Testing: Volume I l 3 Box B--Kevlar R and Twaron R Kevlar R is strong fiber made from polymeric aromatic amide (polyaramid) plastic by dissolving it in a special solvent and spraying the solution through a small nozzle called a spinnerette. The solvent evaporates, leaving the plastic fiber, which has a strength-to-weight ratio about five times that of steel. The possibility of making polyaramid plastic was hypothesized in 1939. It was synthesized and identified at DuPont in 1960, but polyaramid fiber could not be produced until 1965, when Stephanie Kwolek, a chemist at DuPont, discovered a practical solvent. At about the same time, a team at Akzo, Inc., a multinational firm headquartered in Holland, independently discovered a practical solvent and applied for a patent for the manufacture of polyaramid fiber, which DuPont named Kevlar R and Akzo later (1984) named TwaronR. DuPont contested the patent. A consent decree of the International Trade Commission settled the dispute; terms of the settlement included cross-licensing but barred Akzo from marketing Twaron R in the United States until late 1990. Before Kevlar R was used for body armor, it was used as a substitute for steel in the manufacture of radial tires, including those designed for police cars. It does not melt but does pyrolyze (decompose) at very high temperature. It loses some strength as its temperature is increased but remains strong enough to be used for applications requiring high strengthto-weight ratio at high temperature--e.g., in the telescoping nozzles of solid-fuel rocket motors of the Peacekeeper (formerly MX) missile. Kevlar is a registered trademark of DuPont de Nemours and Co., Inc. Twaron is a registered trademark of Akzo, Inc. SOURCE: Office of Technology Assessment, 1992. armor worn by police SWAT (Special Weapons and Tactics) teams for protection from rifle bullets as well as pistol bullets is more familiar to many laymen. Garments of both types are sometimes called bulletproof vests, but no garment will certainly stop any bullet. Indeed, there is no guarantee that a bullet of a type a garment is designed to stop will not kill a wearer. Much of the body is not covered by the protective panels of a particular armor: an astute purchaser may choose a model from the many on the market, fully aware of that coverage limitation. However, the ability of armor to stop bullets--its ballistic resistance -cannot be discerned by inspection; it must be inferred from the results of tests in which sample armor is shot. Because such testing is destructive, vests slated for marketing are not tested. Moreover, the conditions under which an officer is shot are unlikely to be identical to test conditions. In 1972, in an effort to provide police departments guidance in such testing, the National Institute of Law Enforcement and Crimin al Justice (NILECJ), a part of the Department of Justice, issued a standard for ballistic resistance of police body armor, NILECJ Standard 0101.00. It specified general procedures and specific types of bullets and velocities to be used in tests to determine whether samples Example of Tactical Armor Designed for Protection from Rifle Fire SOURCE: Point Blank Body Armor, Inc., 1991.

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4 l Police Body Armor Standard and Testing: Volume I Box CSpectra R and Spectra Shield TM Spectra R is a registered trademark of Allied-Signal, Woven Fabric inc., for the high-strength synthetic fibers the company produces from extended-chain polyethylene (ECPE). Key properties of these fibers (marketed under the brand name Spectra 1000) include low weight and high strength, as well as resistance to impact, moisture, abrasion, chemicals, and puncture. The first successful commercial application for Spectra fibers, introduced in 1985, was as a substitute for steel in ropes and cordage. Other applications that followed include punctureand cut-resistant safety gloves. For soft body armor applications, Spectra fibers are woven into bullet-resistant fabrics or, more commonly, used as a reinforcing fiber in a flexible, nonwoven composite material called Spectra Shield TM introduced in 1988. Thicker, rigid Spectra Shield TM is also made for use as hard armor in helmets, radomes (protective coverings for radar antennas), sonar, and other applications. Spectra fibers are made by a process called gel-spinnin g. Extended-chain polyethylene molecules containing 70,000 to 350,000 carbon atoms are dissolved in a solvent which is heated and forced through tiny nozzles called spinnerets. The resulting jets of solution cool and harden into plastic fibers, which are drawn, dried, and wound onto spools for further steps in manufacturing. This fiber-producing process aligns the extended-chain polyethylene molecules so that the hydrogen atoms of each molecule bond with those of its neighbors. This gives Spectra R a tensile strength greater than aramid fibers. Spectra R is also less dense than other fibers; its specific gravity is only 0.97, so it floats. Pound for pound, it is 10 times as strong as steel. Spectra Shield TM is made by aligning Spectra R fibers side by side and bonding them with a flexible Kraton resin (produced by Shell Chemical) to make a single-ply sheet. Two plies of such sheets are crossed, so that the fibers in one are perpendicular to the fibers in the other, and bonded together. The resulting 2-ply, cross-plied sheet is coated on each side with an abrasion-resistant film to make one thin, flexible sheet of two-ply Spectra Shield TM composite material for use in body armor (see figure). [4] 1 Thicker, multi-ply panels for use as structural armor are made by cross-plying additional layers before coating. A ballistic panel for an armor garment could be made by cutting multiple layers of two-ply Spectra Shield TM into the desired shape, stacking them up like pancakes without stitching them together, and enclosing them in a cloth cover. The cover need not be waterproof, because Spectra Shield TM is highly water-resistant. Exposure to water has no effect on its ballistic resistance. Spectra Shield TM is also highly resistant to degradation by chemicals such as household bleach. Another notable characteristic of Spectra Shield TM is the high velocity-12,300 m/s-at which the stress imparted by a bullet propagates within the armor outward from the point of impact, which allows the bullets energy to be absorbed by a large area of the armor. In the 1 to 2 milliseconds during which a low-energy bullet is decelerated by armor and backing material, [100] part of its energy would be distributed over and absorbed by the entire ballistic panel. Spectra R fabric and Spectra Shield TM can be ignited but only when their temperature reaches 675 F; they are less flammable than cotton or polyester fabrics typically used for police uniforms. Flame-retardant tactical armor has been made by enclosing Spectra Shield TM in a carrier garment made of flame-retardant fabric. Spectra R melts at about 150 *C (about 300 F), but Spectra R fabric retains 94 percent of its room-temperature ballistic resistance at a temperature of 160 *F. Armor so hot would be excruciatingly painful and would bum skin in less than a second, [128] so ballistic resistance at so high a temperature is almost irrelevant. Spectra Shield R stored for 90 days at 160 F and then allowed to cool to room temperature regained its room-temperature ballistic resistance. 2 1 sw dso Gary A. Harpeli et & Ba.Uistic Resistant Composite Article, U.S. Patent 4,623,574, Nov. 18, 1986. 2 viz., Vw meas~~ per MIL-STD-662D using a .22-caL, 17-gr tiagment-simulating ProjeCtie. SOURCE: OffIce of Ik&nology Assessment 1992.

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Police Body Armor Standards and Testing: Volume I l 5Spectra ShieldTM Manufacturing ProcessFlexible resin added/Spectrafiber n Fibers aligned Fibers and flexible resinof armor had certain types of ballistic resistancebased on a quantitative safety criterion and biomedicaldefined in the standard. It was a voluntary performance standard-i. e., armor could be sold without meeting the standard, but if it were tested and passed, the manufacturer could certify this on the label. Armor made from any type of material could, if thick enough, meet the standard. The .00 standard specified a reproducible but arbitrary ballistic test, uncorrelated with physiological protection: There was no attempt to correlate penetration in the test with risk of penetration in service, and it did not attempt to gauge protection from injury by stopped bullets. NILECJ Standard 0101.00 has been supersededthrice: by NILECJ Standard 0101.01 in 1978, by NIJ(National Institute of Justice) Standard 0101.02 in 1985, and by NIJ Standard 0101.03, the currentstandard, in 1987. The .01 standard was the first to beexperiment (shootings of animals) intended to dem-onstrate that samples of armor like those passing thetest would perform as required in service.The current standard, like its predecessors, is necessarily the result of an implicit trade-off among simplicity, economy, realism, reproducibility, risk to consumer, and risk to producer.4 For example, awide variety of bullets impact at unknown velocities in assaults, but, in the interest of reproducibility, thetest requires particular types of bullets to be fired atvelocities varying by no more than 50 feet per second.Each revision had its proponents and its critics, but the latest version evoked unusual controversy when NIJ funded the retesting of all models tested under the .02 program. However, less than half-34 out of 84-of models tested passed under the new standard.5 [151] This surprised NIJ as well as those for each revision is discussed in detail appendix of 5 of era definite of vests passed, indeedof which were tested. The issue is further clouded by the fact that permitted the manufacturers of vests passed under .02 to resubmit them under different designations, and even to submit totally different vests. The Government felt the change from .02 to .03 obliged them to offer a free test, but the manufacturers could choose what vest to test.

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6 l Police Body Armor Standards and Testing; Volume I in industry who had been consulted about the revision. A DuPont spokesman later claimed, Both sides [NIJ and the Personal Protective Armor Association (PPAA), an industry group] agreed was to be no more stringent than [13] The PPAA devised its own standard, PPAA Standard 1989-05, which is demonstrably less stringent but also, the PPAA argues, more realistic and reproducible (i.e., results of similar tests are more likely to be similar). Many purchasers, prospective purchasers, and wearers of body armor have been confused by the controversy, and some manufacturers attribute a decline in sales to the confusion. Critics of the NIJ standard, including some manufacturers of armor material and garments, point to the large fraction of .02-certified models failing the .03 test as evidence of excessive stringency of the .03 test. They point to the mixed results of .03 tests of samples of the same model (sometimes labeled as different models) as evidence that the .03 test yields inconsistent results; some critics have called the test a crap shoot. They question the rationale for crucial aspects of the standard, such as a test intended to gauge protection against serious or lethal blunt trauma (bruising or tearing of internal organs) that could be caused by the impact of a bullet stopped by the armor. They charge that the conservatism of the standard and the variability of test results induce manufacturers to make armor that is heavier, stiffer, less comfortable, and more costly than is necessary to provide the nominal protection certified. Most importantly, they charge that excessive cost reduces sales, and excessive discomfort reduces wearing, of certified armor, with the result that officers who could have been saved by good uncertified armor (or armor certified to comply with a less stringent standard) have been killed not wearing it: Police officers are not dying in defective body armor. Police officers are dying because they are not wearing body armor!! [15] They also believe that the standards controversy itself reduces the sales and wearing of good armor. Defenders of the NIJ standard, also including some manufacturers of armor material and garments, believe that the standards testing requirements and procedures are warranted by the ballistic threats facing police officers and rebut arguments for changing it. They claim the PPAA standard is not stringent enough. They ascribe variation in test results to variation in vest construction. Gross variation in the construction of supposedly identical vestssuch as differing numbers of fabric layers can be seen in the archives of NIJs Technology Assessment Program Information Center (TAPIC). A legislative remedy to the controversy has been attempted twice: Two identical bills introduced in the 10lst Congress, H.R.4830 and S.2639, would, if enacted, have made it a criminal offense to manufacture, distribute, or sell armor not complying with NIJ Standard 0101.03 or any superseding standard issued by NIJ. H.R. 322, a bill introduced in the current (102d) Congress, contains the same language. This report of OTAS assessment of police body armor standards and testing was requested by Senator Joseph R. Biden, Jr. (Chairman), Senator Strom Thurmond (Ranking Minority Member), Senator Dennis DeConcini, and Senator Edward M. Kennedy of the Senate Committee on the Judiciary, Congressman John Joseph Moakley, Chairman of the House Rules Committee, and Congressman Edward F. Feighan of the House Committee on the Judiciary and of its Subcommittees on Crime and on Economic and Commercial Law. The purpose of the study was to clarify the issue of whether NIJ Standard 0101.03 should be revised, and if so, what actions Congress might take. Congress would like to know whether the standard is informative and fair to purchasers and wearers of armor, as well as to manufacturers of armor and its component materials. Purchasers and wearers need to know how confident they can be that certified armor will protect them or to what degree uncertified armor will be less protective. Manufacturers are justified in demanding that the standard not discriminate unfairly against their products. Principal points of uncertainty are: how confident wearers can be that samples of a model, other samples of which have passed the test, will protect them in the line of duty (and under what circumstances); how confident manufacturers can be that testing more samples of the same model would yield similar results; how confident prospective purchasers can be that they wont be defrauded; and whether performance characteristics of dubious value are being tested. Specific points of contention include the following: Whether armor must be tested wet (as well as dry), as the standard specifies.

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Police Body Armor Standards and Testing: Volume I l 7 l l l l Whether armor may be patted down between test shots (which the standard prohibits) to reduce the ply separation (bunching caused by previous shots. The incidence and statistical significance of apparently random variations in outcomes of similar tests, and, if significant, their causes. Whether armor should be failed (as the standard requires) if a nonpenetrating test shot makes a crater deeper than 44 mm (1.73 in) in the material on which the armor is mounted; this is assumed to indicate inadequate protection from the impact of a stopped bullet. The protection afforded by the current standard against false or deceptive advertising or labeling (e.g., of armor as complying with the NIJ standard, when in fact it has not been tested for compliance). In addition, the study was to investigate ancillary issues, such as the shape of the test fixture to which the armor is attached for ballistic-resistance testing and the choice of the backing material (inside the test fixture) against which the armor is placed to be shot. BACKGROUND Soft Armor and Hard Armor Two types of armor are worn by police: soft armor and hard armor. Soft armor, designed to stop handgun bullets, is worn routinely by many officers. It is often worn in a sleeveless undergarment called a vest (see photo) but is sometimes incorporated into the lining of a jacket or other outer garment. It is designed to be inconspicuous, although a person intent on detecting it might discern it under light clothing at close range in daylight. Hard armor is domed, often over soft armor, by police on special assignments expecting an unusual risk of rifle fire or stabbing. It maybe inconspicuous but is often quite distinctive: television viewers recognize it as the armor worn by SWAT (Special Weapons and Tactics) teams (see photo). Police call it tactical armor and generally find it too hot, heavy, or conspicuous for routine wear. It may include panels of sheet steel or titanium, perhaps coated or tiled with ceramic. Most bullets that kill police officers are fired by handguns (see box D). Some soft, concealable body armor is designed to offer protection against the full spectrum of handgun bullets. Lighter, less expensive models offer protection against the most common handgun bullets. Many officers are killed by shotguns firing shot or slugs; soft armor has apparently saved many officers from such projectiles. Many officers are killed by rifles. Soft armor has apparently saved a few officers from carbine fire, 6 but hard armor is usually required to meet the NIJ or PPAA standard for protection from rifle fire. Summary of NIJ Standard 0101.03 A Performance Standard The .03 standard is a performance standard, not a construction standard. It does not specify the area of coverage, nor does it specify any material to be used in the armor. This permits and encourages technical innovation, including the development of materials and designs providing better ballistic resistance, greater comfort, or lower cost. However, some aspects of the standard were introduced specifically to provide stringent tests of likely weak points of Kevlar fabric armor, which at the time was almost the only type of concealable body armor marketed in the United States. Certification of Compliance NIJ Standard 0101.03 provides for the manufacturer to certify, on the label, that armor is of a model that has a type of ballistic resistance defined by the standard if samples of the same model have passed the test specified by the standard for that type of ballistic resistance, regardless of who conducts it. Such a test could be conducted by the manufacturer or by an independent ballistic laboratory under contract to the manufacturer. A manufacturer could truthfully certify a model of armor to comply with NIJ Standard 0101.03 even if it failed the test repeatedly before finally passing it. Partly because of this, a manufacturers certification, by itself, may provide little assurance of design quality. However, manufacturers (or any other interested party) may submit samples of a model of armor to NIJ for NJ-supervised testing by an NIJ-approved 6 A ~bin~ is ~ compact fie tit f~e~ ~~dge~ designed for ~es or pistols, B~ause of its short b~el, it does not accekrate fle bullets tO the velocity they would attain if fired from a longer-bamelled rifle.

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8 Police Body Armor Standards and Testing: Volume I Box DTrends in Weapons and Ammunition Used in Assaults on Police Jurisdictions all across America report an upswing, during the last few years, in the confiscation of guns of greater firepower, as measured by caliber, muzzle velocity (which increases with barrel length), magazine capacity, and rate of fire (e.g., fully automatic). These include so-called assault rifles and automatic pistols (see box E) that fire high-energy ammunition such as .357 Magnum, .44 Magnum, and 9-mm Parabellum (see box F). Officers feel they are more threatened by these guns than they were in the past. [102] Some blame the increase on the affluence of criminals involved in the drug trade; others see it as an unfortunate side effect of the largely successful campaign to ban the short-barreled, small-caliber handguns known as Saturday night specials. Mysteriously, this trend toward long guns and high-energy handguns is barely perceptible in the guns actually used to shoot police officers. It may be that most of the increasingly numerous submachine guns seized were purchased for show or to shoot other crimin als; with few exceptions about one per year-they are not being used to attack police-at least, not yet. The few cases of their use against police-generally with no greater effect than a revolverare highly publicized, which may inflate the perceived magnitude of the threat they pose. The trend toward increased use of high-energy handguns in assaults on police, although slight, is real. Part of the increase is attributable to the issuing of .357 Magnum revolvers or 9-mm automatic pistols rather than .38 Special revolvers by many police departments responding to a perception (or projection) that their officers will face firearms similar to those they confiscate. However, about a fifth of all officers who are shot are shot with their own gun or their partners, so an upgrade of the officers own sidearms increases the threat they face and against which they are well advised to protect themselves. SOURCE: Office of Technology Assessment, 1992. independent laboratory and, if it passes, for certificaA body armor MODEL is a manufacturer designation of compliance by NIJ. NIJs criteria for certifying compliance, which include the standard itself and a host of other memoranda, prohibit accepting armor of a model that has previously failed an .03 certification test. 7 TAPIC, to which samples must be submitted for NTJ-authorized testing and (if successful) certification, inspects samples and attempts to determine whether the samples are substantially the same as samples previously submitted under a previous model name. Armor certified by NIJ is listed on NIJs Consumer Product List, which is maintained by TAPIC. Consulting NIJs Consumer Product List is the only sure way to determine whether NIJ has certified compliance with NIJ Standard 0101.03; this cannot always be determined from the label. Some martion that identifies a unique ballistic panel construction; i.e., a specific number of layers of one or more types of ballistic fabric and or ballistic-resistant material assembled in a specific manner. A body armor STYLE is a manufacturer designation (number, name, or other descriptive caption) used to distinguish between different configurations of a body armor product line each of which includes the same model of ballistic panel. The distinctions between body armor model and style were established to eliminate the necessity of retesting a given body armor model for compliance with the NIJ Standard each time a manufacturer incorporates the model into [a] different style of armor. [145] keted armor is certified only by the manufacturer and NIJ certifies the ballistic resistance of a model on not by NIJ. the basis of ballistic testing of samples of the model in accordance with the standard; NIJ certifies the ballistic resistance of a style on the basis of Models and Styles of Armor inspection of a sample by TAPIC to determine that NIJ notes that For the purposes of the body it does indeed contain a model of ballistic panel armor certification procedures, the following definialready certified to have the ballistic resistance tions have been adopted: claimed for the style. Thus all styles of the same 7 we &s@@sh~~=n~~s cert~l~tion tniter@ which require one test according to NLJ Standard 0101.03 and have o~m r~fiements as we~~ and the ballistic test specified by the standard, which maybe performed for NJ certifkation or for other purposes, such as manufacturers certification of compliance or testing samples of certified models for quality assurance (commonly called retesting).

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Police Body Armor Standards and Testing: Volume I l 9 Box ETypes of Guns Firearms are classified according to barrel length as handguns or long guns; the latter include rifles and shotguns. Handguns and rifles (and some shotgus) are generally designated by their caliber and by the nature of their firing action. The caliber is the inside diameter of the barrel. Thus .22s have barrels with an inside diameter of 0.22 inch, and that of mm guns is 9 millimeters. Anomalously, .38 Specials have barrels with the same inside diameter as that of a .357-caliber revolver: 0.357 inches. While the .38 Special cannot fire the longer or magnum .357 ammunition, the .357 revolver can fire .38 ammunition. 1 The designation .380 is used for automatics firing .38 caliber (i.e., .357 -inch) bullets from specialized cartridges. The +P designation appended to some .38 Specials indicates that the gun can withstand the high chamber pressure exerted by +P ammunition. With the exception of the .410-caliber shotgun, a shotgun is measured by reference to a (now largely hypothetical) musketball-style lead sphere that just fits in the barrel: the gauge of the shotgun is the number of such balls one could make from a pound of lead. Therefore a smaller gauge number denotes a larger gun. The most common sizes of shotgun are the 12 and 20 gauges; if measured in inches these would be approximately .80 and .68 caliber, respectively. If .410 shotguns were measured in terms of their gauge, they would be 90 gauge. There also exist shotguns of gauges 28,16, and 10. Other anomalies abound. For example, while the .30-06 and the .30-30 rifles use the same .308-inch diameter ammunition, the of the formers designation refers to its year of adoption by the military, while the second in .30-30 refers to the (original) weight of the latters powder load, in grains. Actions are often designated full automatic, automatic, semi-automatic, autoloading, double action, single action, bolt action, lever action, and pump. These terms divide the weapons according to what the firer must do to fire repeated shots. Full automatic weapons will fire continuously as long as the trigger is pulled back, until they run out of ammunition (or until they jam). Semi-automatic, double action, and autoloading weapons require a separate trigger pull for each shot. Single action weapons require cocking between shots; bolt action, lever action, and pump rifles and shotguns require operation of their bolt, lever, or pump between shots. The terms automatic and semiautomatic are not always correctly used or understood. Regarding handguns, automatic is used in contradistinction to revolver; the Colt .45 M1911al (familiar for decades as the U.S. militarys sidearm) is an automatic whereas the Colt .45 Peacemaker (of cowboy fame) is a revolver. Automatic handguns fire in the manner called semiautomatic for other guns: shots can be fired in rapid succession by repeatedly pulling the trigger, without any other action such as operating a bolt, pump, or cocking leverbut so do most modern revolvers. (Some products of the Ruger Arms company and the Colt Peacemaker, which appeared in 1873, do not.) Otherwise, automatic is properly used to describe full automatic guns, i.e. machine-guns: guns that will continue to fire as long as the trigger is depressed. (Most such guns have a selective-fire switch, allowing the user to toggle between full automatic and semiautomatic modes of operation.) A submachinegun is a machine gun that fires pistol ammunition. A carbine is a compact rifle. Attempts to define the term assault rifle for legal purposes have met with great difficulty because these guns differ from other semiautomatic carbines largely through styling, not functionality. 1 mS ~~ -e it tilc~t to establish What ~ of ammunition was used in an assault which makes reenactment problematical. SOURCE: OffIce of lMmology Assessment, 1992. model are assumed to have the same ballistic stitching of ballistic panels (e.g., box stitch versus resistance. quilt stitch) would make the panels different models. TAPIC considers garments differing only in color Types of Ballistic Resistance to be of the same style. Differences ir-the size or cut The .03 standard defines six standard types of (i.e., shape) of garments would make them different ballistic resistance for which armor may be tested styles, not different models, even though size and cut and provides for custom testing for special type possibly affect ballistic resistance. Differences in ballistic resistance. Each type is defiied in terms of 327-115 0 92 2 : QL 3

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1O l Police Body Armor Standards and Testing: Volume I Box FABCs of Ammunition, Bullets, and Cartridges 22-cal. KmD .25-cal. ED .32-cal. m .380-cal. D .38 Special m .357 Magnumm 9-mm. ED .44 Magnum u== .45-cal. (Em Pistol and rifle ammunition is described in terms of the diameter of the bullet, the length of the cartridge, and the shape and composition of the bullet. Shotgun ammunition is described in terms of the diameter (gauge or caliber) of the gun barrel for which it is designed, and by whether it contains a single bulletlike slug, or if not, by the size of the shot or pellets it contains. Bullet diameters are, of course, the same as the inside diameters of the gun barrels from which they are fired. The sizes and nomenclature of these were discussed in box E. The length of the cartridge has a direct bearing on the amount of powder it can contain and thus on the velocity with which it can propel the bullet. Magnum cartridges are longer than standard cartridges to contain more powder. Likewise, many handguns are chambered for .22 Long Rifle cartridges, which contain more powder than .22 Shorts. Bullets vary in shape, construction, and composition. The shape can range from the relatively pointed Speer bullet, no longer used in body armor testing, to the cylindrical wad cutter bullet optimized for the clean punching of circular holes in paper targets. The semi-wadcutter shape is a compromise between the wadcutter and the typical domed bullet shape. HollowPoint bullets feature a small cavity in the nose, to create mushrooming after impact. Some controversy surrounds the question of whether nominally identical bullets differ sufficiently in shape to affect the outcome of armor tests. Bullets can have full or partial metal jackets. A partial jacket, typically found on a hollow point bullet, leaves the nose of the bullet exposed. The jacket is typically made of copper, though copper-clad steel jackets are not unheard of. A gas check is a copper shield on the base of the bullet to keep the burning gunpowder from melting the base while the bullet is still in the gun. Jackets and gas checks aside, bullets are normally made out of lead. The hardness of this lead is governed by the degree to which it is alloyed with other metals. Some bullets contain harder metals, either in the form of steel balls cast into the lead or, in the extreme case, machined steel, brass, or even tungsten bullets coated with copper or Teflon. These bullets are designated armor piercing. Armor piercing military rifle bullets, such as those used in testing Type IV armor, consist of a steel core covered by a full copper jacket. Some have lead bases or point fillers. The rare Teflon-coated bullets made of machined steel, brass, or

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Police Body Armor Standards and Testing: Volume I l 11 tungsten have gained notoriety far out of proportion to Shotgun loads range from birdshot loads containing their number. Originally designed for use by police hundreds of small pellets to the slug load, composed of officers in shooting through cars, they received their a single bullet-like slug. Buckshot lies between cop killer nickname later, when soft body armor these extremes, with a shell containing a dozen or so was introduced. They will penetrate soft body armor, pellets, depending upon the size of the buckshot. To but no armor-wearing officer has been killed by one. 1 make up for the lack of rifling inmost shotgun barrels, The Teflon in itself confers no special armor-piercing slugs themselves are typically rifled, i.e., cast with properties, and is used merely to lessen the extreme slanted grooves on their sides to impart aerodynamibarrel wear that would otherwise be caused by bullets cally the spin needed for stability. made of such hard materials. 1 TWO offl~ers Wae killed by such bullets in 1967, before the introduction of soft body armor into kv ~OrCment use. SOURCE: Office of lMnology Assessment, 1992. the type or types of bullets fried at panels of the armor to test its ballistic resistance (see table 1). Two types of handgun bullets are fired to test for Tjq?e I, It-A, II, or III-A ballistic resistance, which soft armor can provide. One type of rifle bullet is fired to test for T~e III or IV ballistic resistance, which hard armor can provides Each standard type of armor is expected to offer protection against the threat associated with it as well as against the threats associated with all other standard types of armor appearing above it in table 1. For this reason, the types of armor defined by ND Std. -OlOl.O3 are often referred to as levels, level Ii-A being presumably superior to level I, for example. However, a certification test for type II-A ballistic resistance would not actually test resistance to type I threats. In addition, an NIJ guide speciiles other threats against which it expects armor of each standard ballistic-resistance level to provide protection (see table 2), even though the .03 test does not actually test resistance to such threats. [145] Selection of Samples The NIJ standard specifies that Four complete armors, selected at random and sized to fit a 117 cm (46 in) to 122 cm (48 in) chest circumference, shall constitute a test sample. (Note: The larger the size, the more likelihood that all ballistic testing will fit on just two complete armors.) In quality assurance, Table lTypes of Ballistic Resistance Defined by NIJ Standard 0101.03 in Terms of Bullets and Velocities Specified for Testing Bullet mass lmpactvelocit~ Type Bullet caliber and type (grains) (ft/s) I .22 long rifle high-velocity .38 round-nose lead II-A .357 jacketed soft-point 9-mm full metal jacket II .357 jacketed soft-point 9-mm full metal jacket II I-A .44 magnum lead semiwadcutter gas-checked 9-mm full metal jacket Ill 7.62 mm full metal jacket Iv .30-06 armor-piercing Special custom 40 158 158 124 158 124 240 124 150 166 custom 1,050 850 1,250 1,090 1,395 1,175 1,400 1,400 2,750 2,850 custom %finumum velocity; the maximum velocity for a fair hit is 50 ftls greater. SOURCE: National Institute of Justice, 1987 [144]. selected at random usually means selected at random with uniform probability i.e., sampling should insure that all units of the model should have the same chance of being selected to be tested. However, this is impossible if samples are selected for certification testing before production of the model has been discontinued. Tjq?ically samples are selected after only a few units have been produced; consequently, the sampling procedure does not guarantee that the samples are representative of 8 me test ~roc~we for ~~spec~ ~e$$ b~li~ti~ resis~m is the s~e as for s~@d types of b~istic resis@n&, except the person ordering tbe testing (e.g., a manufacturer) specifies the type and nominal velocity of the test projectile to be used. For example, a manufacturer could have armor tested for W certification of Special ~pe ballistic resistance to a .45-caliber bulleq a 12-gauge rifled slug, or buckshot at a specified velocity, Special-type armor is not necessarily expected to protect against the threat associated with any other type.

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12 l Police Body Armor Standards and Testing: Volume I Table 2Types of Ballistic Resistance Defined by NIJ Standard 0101.03 in Terms of Guns and Ammunition Against Which Protection Is Expected Type Threat I .22, .25 and .32 caliber handguns, .38 Special lead round-nose II-A .38 Special high-velocity, .45s, low-velocity .357 Magnum & 9-mm, .22 rifles II Higher velocity .357 Magnum and 9-mm III-A .44 Magnum and submachine gun 9-mm Ill High-power rifle: 5.56mm, 7.62mm FMJ, .30 carbine, .30-06 pointed soft point, 12-gauge rifled slug Iv Armor-piercing rifle bullet, .30 caliber (1 shot only}. SOURCE: National Institute of Justice, 1987 [144] and 1989 [145]. yet-to-be-produced units of the model, particularly of smaller sizes. Conduct of the Test Armor to be tested is mounted on a flat block of inelastic backing material-typically modelling clay to be shot. The impact velocity of each bullet is measured using a ballistic chronograph (see figure 2). If the bullet hits an appropriate point on the panel at an impact velocity within specified limits (see table 1), the impact is considered a fair hit. The test requires a fair hit in each of six specified areas on each panel in a specified sequence (see figure 3). Each shot must impact at least 3 inches from the edge of the panel and at least 2 inches from the closest point of impact of any prior shot. In tests of Type I, II-A, II, or III-A ballistic resistance, four complete armors, typically including eight armor panels (four each front and back) are usually shot. Each ballistic element (front or back panel) is sprayed with water and then shot with test bullets of the first type, then another one is sprayed and shot with test bullets of the second type. This is repeated with unsprayed, dry samples. This requires a minimum of 48 shots per test: 2 element types (front and back) x 6 shots each x 2 types of test bullets x 2 wetness conditions. If the velocity of a shot is too low and it does not penetrate the panel, or if the velocity of a shot is too high and it does penetrate the panel, the shot is repeated, aimed at least 2 inches from the closest point of impact of any prior shot. However, no more than eight shots (of one caliber) may be fired at any panel. 9 The armor cannot be certified if any fair shot penetrates. After the first fair shot at each panel, the panel is removed from the backing and the depth of the crater (called the backface signature or BFS) is measured. If the BFS exeeds 44 mm or if the armor was penetrated, it fails; if not, the panel is replaced on the backing without filling the crater or otherwise reconditioning the backing material, and testing for penetration is resumed. l0 The standard prohibits adjusting a panel (e.g., patting it down) thereafter, unless it is reused for testing with a second type of bullet. NIJ Standard 0101.03 specifies that armor be tested on a block of backing material at least 4 inches thick and of sufficient length and width to completely back the armor part to be tested. The standard does not specify unambiguously that the backing must be flat, and in fact requires it to be built up to achieve contact with the armor when testing female armor with bust cups or when testing rigid armor for Type III or IV ballistic resistance. However, in practice, a flat surface is used in other cases. Until recently, the testing of a whole armor garment with removable ballistic panels (the usual configuration) was precluded by the requirement that each ballistic element (e.g., panel) be tested separately. (Although the standard explicitly allows testing a whole armor garment if it is made in one part without removable ballistic panels, this may be precluded by the provision that requires the backing to be of sufficient length and width to completely back the armor part to be tested.) In a letter dated April 27, 1992, NIJ directed H.P. White Laboratory, Inc., that effective June 1, 1992, it should test samples for compliance with NIJ Stand$J To provide for contingencies, six complete armors (12 panels) must be submitted for a Me I, ~-A, ~ or ~-A test. 10 ~ s~dad 0101.03 specfles tit teS~g s~l be continued titer ~ch BFS m~s~ment if it is no ~eater than 44 mm, md ilftti shoot@ Sk fti shots per panel if none penetrated. It neither requires nor prohibits continuation of the testing in other cases-i.e., after failures. However, NJ has directed H.P. White Laboratory, Inc. (HPWLI), the only laboratory authorized to conduct testing for NIJ certiilcation, to complete the testing despite disquali.tlcation of the armor.

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Police Body Armor Standards and Testing: Volume I l 13Figure lCertification That a Model of Armor Complies With the NIJ Standard IsBased on Inspection and Testing of Samples Submitted by the Manufacturer Production Certification testingu I l ItsSOURCE: Office of Technology Assessment, 1992.ard 0101.03 by mounting the whole armor garment on a smaller clay block in a curvilinear frame (see photo)--a highly abstract mannequin.11 The standard itself was not changed. This summ ary does not cover all details of the standard; the interested reader is referred to the standard itself and to appendix A of this report foradditional details.Validity of the TestThe standard does not explain the rationale for its provisions but does refer readers to an NIJ guide that discusses the origin of the standard briefly and citesdetailed reports of research considered by the drafters of the standard. The standard specifies how to conduct a ballistictest of samples of a model of armor under controlledconditions, in order to measure properties of the samples (types of ballistic resistance) that can reasonably be expected to be related to the protec-tion that other samples of the same model will affordwearers in service. However, the details of the relationship are uncertain and disputed; no body of data reliably links performance in the lab withperformance in service. This situation is common inconsumer-product safety testing, but it leaves roomfor legitimate questioning of the meaning of passing the test.FINDINGSBenefits of Wearing ArmorBody armor saves lives and could save more if worn more often by more officers. Wearing armor has saved about 10 to 30 sworn police officers from fatal gunshot wounds each year in recent years. Thenumber saved each year would roughly double if all officers wore armor at all times. Wearing armor alsosaves officers from death or serious injury in other types of assaults and accidents, especially vehicle accidents. By industry estimates, armor has saved over 1,300 police from death or serious injury by firearms assaults (about 40 percent), other assaults (about 20 percent), and vehicle and other accidents(about 40 percent). [18] to Standard 0101.03) is to be done of test certification test.

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14 l Police Body Armor Standards and Testing: Volume IFigure 2Instrumented Ballistic Test Range for Testing Armor as Specified in NIJ Standard 0101.03 Line ,flight B ,/stop trigger / / -StartI ChronographA -5 m for type 1, II-A, II, and II I-A armors; 15 m for type Ill and IV armors. B -2 m minimum C Approximately 0.5 to 1.5 mSOURCE: National Institute of Justice, 1987.However, even universal wearing of armor wouldnot save officers from fatal gunshot wounds inunprotected parts of the body or from some guns and ammunition more powerful than those the armor wasdesigned to protect against (see figure 4).12Factors Influencing Wearing of ArmorPolice departments can promote the wearing of armor by1.2.3. 4. 5.purchasing and issuing it or reimbursing officers for purchasing their own armor, ensuring that it fits, encouraging or requiring officers to wear armor when on duty,13ensuring that chiefs and other supervisory officers set a good example by wearing armor, and instructing officers in the donning and laundering of armor and in the benefits ofFigure 3-Sequence of Aim Points on Each PaneI,as Specified in NIJ Standard 0101.03 ------- .- ------ --All shots at least 7.6 cm (3 in) from any edge and at least 5 cm (2 in) from another shotSOURCE: National Institute of Justice, 1987.Figure 4How Fatal Bullet Wounds in the Torso Would Decrease if the Wear Rate IncreasedTorso wounds and wear rate100%I0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Wear rateSOURCE: Office of Technology Assessment, 1991.wearing armor and the limitations of itsprotection.Discomfort is probably the main reason why someofficers who own armor do not always wear it. Wearers (and, especially, nonwearers) commonly describe their armor as hot, heavy, stiff, chafing, and the like. Complaints about chafing, Soft body armor has a good record of protecting wearers against ammunition more powerful than those it was advertised or certi.tied to protect nevertheless, in some eases rifle bullets and other high-energy bullets have penetrated armor not designed to stop it.13 off some cases whilemoonlighting as a private security guard.

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Police Body Armor Standards and Testing: Volume I l 15Figure 5Wear Rate Versus Temperature-Humidity Index (THI)Wear rate 100%1 Style 1 90% Style II 80% Style II, 10-plyI 12-ply 60% 50% 40% 30% 20%10% 0%vo~ 405060 7080 Temperature-humidity index (THI)SOURCE: Aerospace Corp., 1977.and to some degree about stiffness and the impression of great weight, may be the result of a bad fit, or of strapping the armor on too tightly. Ensuring good fit can encourage wearing of armor. Officers complaints that armor makes them feel hot, however, cannot be attributed to improper fit.Not only is armor material a good thermal insulator,it also blocks the evaporation needed for the bodys normal perspirative cooling. A large, year-long survey conducted by the Aerospace Corporation for the NILECJ found that the strongest influence onwear rate (of those considered) was the Temperature-Humidity Index (THI).14 Reported wear rates were higher at times and locations with lower values of the THI (See figure 5.), and higher in the winter months than in the summ er. (See figure 6.) [7] Some officers find they can lessen this blockingeffect of the vest by wearing a special undergarmenthaving vertical ribs designed to hold the vest away100% 90% 80% 70% 60% 50% 40% 30%20%1 o%Figure 6-Wear Rate Versus MonthWear rate Style I Style II Style II, 10-ply 12-ply 14-ply -6 18-ply 24-Ply 0%I I I III IJFM AMJJ ASOND MonthSOURCE: Aerospace Corp., 1977.from the body and allow circulation of air under thevest.Complaints about the weight of the vest are of particular concern, because weightunlike chafing or heat retentionis directly related to the ballistic resistance of the vest. Stopping heavier, faster, harder bullets makes the vest heavier, as does protecting a greater fraction of the body. Thus,insofar as weight lessens comfort, there exists a truecomfort-v. -protection tradeoff. However, an analysis of the Aerospace Corporations survey data indicates that wear rate does not decrease markedly with increasing coverage or armor weight until theweight of armor material per unit area exceeds about4.5 kilograms per square meter, which is typical ofmodels certified to have type II-A ballistic resistance(see figure 7).15 Lighter armor with less ballistic resistance was not worn more, but heavier armorwith more ballistic resistance was worn slightly less. defined the Temperature-Humidity Index by the formula = 15 + 0.4 x (T + where T = @9, and = wet-bulb temperature (?F). Officers Participating in to armor; other things being equal, officers not obliged or ordered wear armor might be less likely to wear it than other officers, and their wear rate might show greater sensitivity to weight per unit although this is speculative.

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16 l Police Body Armor Standards and Testing: Volume IFigure 7Wear Rate Versus Areal Density of ArmorWear rate (12-month average) 100%I Wraparound vests Front/back only 80%I60% ) + 20% -o% Io1234567Areal density (kg/sq m)SOURCE: Office of Technology Assessment, 1992, based on data from Aerospace Corp., 1977.Departments that are contemplating purchasing heavier armor should consider that the greater protection it could provide may be offsetby a lower probability that it will be worn. Detailswill depend on region, season, type of duty, and individual physiology. This is less of an issue for tactical armor that can be tolerated for limited periods of high risk, even though uncomfortablyheavy.Goals of Testing and CertificationPurchasers and wearers of armor want to knowwhether a model of armor will protect them againsta specified threat. Unfortunately, testing can only estimate the probability that the armor will stop aspecified bullet and prevent the impact from injuringthem. The estimate could be wrong, because identical tests of identical samples of armor may yield different results, and because the validity of the test (the correlation of its results with performance in service-see box G) is uncertain. Experiments designed to gauge the validity of a test can measurethe statistical confidence (see box H) with which onecan conclude that armor that passes the test would limit probability of injury to whatever level maybe required. However, the assessment of the validityof existing or proposed test procedures cannot beobjective or conclusive unless NIJ specifies the maximum acceptable risks of specific types of injuries or incapacitation by penetrating and nonpenetrating bullets, and the statistical confidence with which the validity of the test must bedemonstrated.A test of ballistic resistance would be called valid if armor that passes it is adequately safe in service. Hence, one cannot decide whether a test is valid unless adequately safe has been defined. Moreover, one cannot decide whether a testis valid unless adequately safe has been defined probabilisticallyi.e., by specifying the maximum ac-ceptable probabilities of specific types of injuries or incapacitation under specific conditions. These maximum acceptable probabilities must begreater than O percent; no armor can be expected toprotect a wearer with certainty, desirable though thatmay be. Even if, hypothetically, it could, that could not be shown scientifically. If, however, a nonzero maximum acceptable probability of each type of injury to be avoided were specified, then analyzing medical and ballistic data from shootings of persons wearing armor (primarily assaults onpolice officers) and subjecting the victims armor to

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Police Body Armor Standards and Testing: Volume I l 17 Box GStringency, Validity, and Reproducibility In this report, a test of ballistic resistance, such as that specified by NIJ Standard 0101.03, is called stringent if a sample of armor has a high probability of failing it. Of course, the probability varies from sample to sample, so the term has only relative (not absolute) meaning. 1 Nevertheless, no matter what the probability is, certain changes in the test can increase it; others can decrease it. For example, requiring the sample to withstand more shots while allowing no more penetrations would increase any samples probability of failing the test, hence it would increase the stringency of the testIncreasing the stringency of a test may not make it better. Whether it does depends in part on the validity of the test. In this report, a test of ballistic resistance is said to be valid if armor that passes it is adequately safe in service. This term, too, is relative--validity depends on the safety criterion to be met. In any case, if the results of a ballistic test are completely unrelated to the performance of armor in service, the test would be invalid.. Valid tests may be have different types and degrees of validity; to describe them precisely and distinguish them requires statistical terminology (e.g., correlation between test outcome and penetration in service). Whether increasing the stringency of a test is judged to be an improvement also depends on the judges stake on the outcome. If a mandatory test is invalid, making it more stringent would strengthen whatever restriction it imposes arbitrarily on the freedom of the producer to sell, and the freedom of the consumer to buy, any armor they please. If a mandatory testis valid, making it more stringent would increase the degree or the certainty of the protection it provides a wearer, which would be good for the wearer, other things being equal. But, depending on how it is done, increasing the stringency of the test might also fail the only armor that some would-be purchasers consider affordable (this would decrease sales), or the only an-nor that some potential wearers find comfortable enough to wear routinely (this would decrease wearing and might decrease lives saved). Others might find armor passing the more stringent test less comfortable, even though they tolerate and wear it. Clearly, different stakeholders will weigh the advantages and disadvantages of increasing the stringency differently. If the test is voluntary rather than mandatory, the effects would be less stark but more complicated to assess. A tests validity is distinct from its realism. A test that shot each sample of armor with one bullet, fired from a gun (and a cartridge) drawn at random from those confiscated by police would be more realistic than the NIJ-specified test. The result of one such test would not be a reliable indicator of how armor like the sample tested would protect a wearer in service, nor could the same result be expected to be obtained in another test of a similar sample of armor. Conversely, tests designed to predict protection reliably would use many shots by a more limited variety of bullets than assailants use and would test several samples of armor. A major concern of producers and purchasers alike is the reproducibility of a test, which could be defined as the probability that successive tests of identical samples will yield the same results (if the testis a pass/fail test) or results within specified limits (if the result of the test is a score). However, it is impossible to determine the reproducibility of a test, according to either of these definitions, because one cannot measure either probability. A more practical but more complicated approach is to define the reproducibility of a pass/fail test in terms of lower confidence limits (corresponding to various confidence levels) on the probability that a sample will pass a test, given that an identical sample passed an identical test. Similarly, the reproducibility of a test that results in a score may be defined in terms of confidence limits on the probability of obtaining a score within specified limits, given that an identical sample attained a score within the same limits. Actually, no two samples will ever be identical, nor will a test be conducted in exactly the same manner each time. Even if identical samples were tested in exactly the same way, the results could differ because of fundamental physical reasons. This makes it difficult, if not impossible, to scientifically test whether an observed variation in test results should be attributed to a variation of test procedure or, alternatively, to a variation of armor samples. In some cases, subsequent investigation has found a variation of either test procedure or armor samples that might have influenced the test results, but this does not prove that the variation was the sole cause of the differing results. 1 F~~oro, ~ pro~bi~ty that a partic&u S-plc will fail a test cannot be determined even after testing-it a o~y b esmt~+ SOURCE: OffIce of lkchnology Assessment, 1992. 327-115 0 92 3 : QL 3

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18 l Police Body Armor Standards and Testing: Volume I Box HStatistical Confidence The idea of probability is clear to most of us: we understand the statement that vest X has a 91 percent probability of stopping bullet Y going Z feet per second. Yet many statements about these probabilities are couched in terms of statistical confidence, as in percent confidence that vest X has at least a 91 percent probability of stopping bullet Y going Z feet per second. This sounds like an extra layer of waffling. Why is it needed? It is needed because we can never test enough vests to be sure that the stopping probability is exactly 91 percent. After 100 shots and 9 penetrations, 91 percent would be a best guess (a maximum-likelihood estimate: the probability that would have made the test results more likely than any other probability would). However, the true value could be 90 percent or 92 percent. Even after 1,000 shots with 90 penetrations, we cant be sure that we havent been a little lucky or a little unlucky in our shooting. For this reason, we need to express probabilities in terms of a level of confidence (such as 90 percent) that the true value lies in some range, called a confidence interval, that depends on the test results. For example, 100 shots with 9 penetrations gives 90 percent confidence that the stopping probability is at least 86 percent and 99 percent confidence that it at least 82 percent. This means if the stopping probability were no greater than 86 percent, there would have been a 90 percent probability of getting more penetrations than we did (9), and if the stopping probability were no greater than 82 percent, there would have been a 99 percent probability of getting more penetrations. Conducting more tests narrows the range of probabilities (the confidence interval) that corresponds to some confidence level. For example, a total of 1,000 shots with 90 penetrations (the same fraction) gives 90 percent confidence that the stopping probability is at least 90 percent and 99 percent confidence that it is at least 89 percent. SOURCE: Office of Technology Assessment, 1992. the ballistic test in question, using bullets of the type confidence or decreasing the significance required with which it was shot (this is called a reenactment increases the number of reenactments required to of the test to which the armor might have been decide validity. subjected before being used) would allow the validity to be decided scientiilcallyi.e., with an Once validity is decided, the issue of appropriate appropriate level of statistical confidence, if the test stringency will be clarified: is accepted as valid, 16 or with an appropriate level of statistical signficance, if the test is rejected as l invalid. 17 What levels of statistical confidence and statistical significance are appropriate? The former must be l less than 100 percent and the latter greater than O percent, otherwise an infinite number of reenactments would have to be performed. Aside from this, the choice is entirely subjectivea matter of acceptable risk. To avoid future controversy over such matters, NIJ should specify the levels of statistical confidence and statistical significance it deems appropriate for deciding validity. It may, however, take months or years to collect enough data to decide the validity of a test with the confidence or significance required. Increasing the Invalidity is rejected with the statistical significance required by NIJ, the test should be changed. If validity is accepted with much more statistical confidence than the minimum required by NLJ, then it could also be concluded, with the minimum confidence required by NIJ, that to pass the test, armor must provide greater safety than required by NH-equivalently, that some adequately safe armor would fail, which would be unfair to its manufacturer. This would also argue for changing the test. However, no matter what the test, there is always some chance that adequately safe armor will fail. To preempt debate on this issue, NIJ should specify a maximum acceptable probability that safe armor 16 Here statistical confiden~ refers to the probability that the test would have been rejected as invalid erroneously, if the probability of m fijq to be avoided were as great as the maximum acceptable probability of injury, which in this context is called the upper contldence limit on the probability of injmy. 17 Statistic significan~ refers to the maximum probability that the test has been rejected as invalid erroneously, i.e., the probability that the test would have been judged invalid if the probability of an injury to be avoided were as great as the maximum acceptable probability of injury.

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Police Body Armor Standards and Testing: Volume I l 19 will fail-a maxim um acceptable producers risk, in the parlance of quality control. l If validity is accepted with little more statistical confidence than the minimum required by NIJ, it cannot be argued that the testis (much) more stringent than necessary to meet the safety goals. To charge excessive stringency would be to charge that NIJ requires greater safety for wearers than the critic deems appropriate. It should be recognized that this is an essentially political issue, not a scientific one. In 1976, NILECJ specified the maximum acceptable risk of death or serious injury by nonpenetrating bullets, 18 but did not specify the statistical confidence with which acceptable risk must be demonstrated. [106] The safety goals, which were proposed in a 1973 Army study for NILECJ, [104] have been phrased differently in different reports by those associated with NILECJS Lightweight Soft Body Armor Program. [74, 106, 145] This has caused some confusion about the precise meaning of the goals; clarification will be necessary in order to test the validity of the standard scientifically. Moreover, NILECJ did not specify any maximum acceptable risk of penetration; it said only that armor should prevent penetration by the bullet into the chest, abdomen, or back. If this means that no risk of penetration is acceptable, no test could determine whether armor satisfies this criterion: no matter how many tests resulted in no penetration, there would be no guarantee that the next shot would be stopped. A realistic goal would specify some nonzero maximum acceptable risk, and some statistical confidence with which it must be demonstrated. Much of the current controversy over armor standards and testing arose and persists because the certification procedure does not quantify the risks, and the uncertainties in the risks, to manufacturers, purchasers, and wearers. A risk for the manufacturer is that samples of a model will be tested and certified, and that samples produced later will be retested and fail. This has happened a few times. In some cases, no visible difference between the retest sample and the sample tested for certification was found. Concerning one such case, TAPIC wrote, It is apparent that when a marginal vest is submitted for multiple tests, it is to be expected that some will pass and some will fail. [32] OTA concurs, but notes that marginal design or variations in production are not the only possible causes of variation in test results. Part of the variance of test results might be caused by subtle variations in test procedure. 19 Although experiments can be designed to estimate the effect of deliberately controlled variations in samples or test procedure on the variance of test results, OTA knows of no way to attribute fractions of the unexplained variance of test results to (1) variations in samples, (2) variations in test procedure, and (3) irreducible randomness. Probably all contribute in some unknown proportion. Apart from the problem of assigning blame for variation in test results to various hypothesized causes, there are fundamental limits to the amount of information that the passing of a certification testany certification test--can provide about the probability that identical samples would pass an identical retest. Statisticians describe the limits in terms of the statistical confidence with which one can conclude that the probability of passing a retest is greater than some number called a lower confidence limit. Statistical confidence refers to the probability that the test would have been failed if the probability of passing it, or an identical retest, were as low as the lower confidence limit. The greater the lower confidence limit, the lower the statistical confidence with which one can draw such a conclusion. 20 18 Btilets stopped by -or often bruise or lacerate the skin behind the armor. Usually such injuries are fior; they do not ficapacibte the victim (they often go unnoticed!) and require no surgery. However, a fast or heavy projectile stopped by light armor may bruise or rupture vital organs; this is called blunt trauma if unaccompanied by severe skin laceration. However, a bullet may even push armor into the skirL producing not only laceration but what surgeons call a penetrating wound, even though the armor is not penetrated. 19 AII ines~bl~possibly very small-part is caused by the irreducible, quantum-mechanical randomness of physical phenomem. 20~ tie pmbabdi~ of Pmsfig a ~fiation test or ~ identi~ retest wme 1/2, the probability tit the ce~lcation test WOW k ftdd wotid k 1/2. Thus cemj5cation provides only 50 percent statistical confidence that the probability of similar samples passing a retest is at least 1/2. It provides only 40 percent confidence that similar samples will pass a retest with a probability of at least 60 percent, 30 percent con.tldence that similar samples will pass a retest with a probability of at least 70 percent etc.no matter howmuchcare is taken to make the samples of armor and test procedure uniform. Certification likewise provides only 50 percent confidence that similar samples will pass both of two retests with a probability of at least 1/4, or three of three retests with a probability of at least 1/8, etc.

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20 l Police Body Armor Standards and Testing: Volume 1 Details of the test, such as whether armor is repositioned between shots, may affect the probability with which samples will pass a test, and if they are known to differ from test to test in a systematic way, such tests would not be identical. Steps can be taken to eliminate some possible sources of systematic test-to-test differences (see below), but it is doubtful all possible sources could be eliminated, and it is certain they could not be proven to be eliminated. Even if they were eliminated, one test could provide only limited statistical confidence (see fh. 21) in the corresponding confidence limits. This is not widely recognized; NIJs criteria for certification and recertification should recognize such uncertainties explicitly and should advise manufacturers, purchasers, and wearers. 22 It is not essential that the ballistic resistance of armor be tested under rare, extreme environmental conditions, provided customers understand the limitations of the testing. It would be reasonable for NIJ to specify optional tests for ballistic resistance under such conditions and to certify compliance of armor passing such tests at an approved testing laboratory. Such tests would increase the cost and stringency of tests while providing diminishing returns in terms of risk reduction, because shootings of officers under such conditions are rare. It would be reasonable to require ballistic testing only under those conditions that research shows affect ballistic resistance substantially and occur at least 10 percent of the time when armor is worn. Allowing ballistic testing under less common conditions to be optional would permit (but not require) consumers to accept the risk that the actual ballistic resistance of armor could be less than the certified ballistic resistance up to 10 percent of the time. This does not mean the armor would be penetrated, or the wearer killed, by 10 percent of all bullets that hit armor; that would be the worst possible case. Even so, the risk, although unknown, could be significant, and NIJ might be unwilling to allow consumers who would accept it to buy armor certified by NIJ to provide a level of ballistic resistance only 90 percent of the time. Nevertheless, there are arguments for accommodating such consumers: l l l l l l Designing armor to have rated ballistic resistance under some rare conditions may make it uncomfortable and decrease the probability it will be worn under all conditions. The validity of a test of ballistic resistance under a rare condition may not be demonstrable with reasonable confidence (at least, for several years) because few or no cases suitable for reenactment may occur. The costs of the extra testing required, which would be passed on to consumers, would be avoided. Consumers could (and should) be told of the conditions for which the rated ballistic resistance is certified, and of the most commonly occurring conditions known or believed to be detrimental and for which ballistic resistance is not certified. Consumers, thus informed, could decide to accept the risk. Optional standard tests for ballistic resistance under the more common rare conditions (e.g., wetting) should be specified for the benefit of purchasers who demand it and are willing to pay the passed-on share of the cost of the extra testing. There are precedents for accepting comparable or greater risks in return for economy, comfort, and other benefits. For example, in 1976 NILECJ stated the following goal for lightweight body armor: Any blunt trauma effects requiring surgical repair should have a mortality risk of 10% or less. 23 [106] As another example, police officers rarely wear (and few possess) helmets providing ballistic protection, even though more than half of the officers killed wearing armor were killed by head wounds. 24 21 me c~c~atiom above assume the probability of passing a test or retest rem constan~ although unknown. However, a systematic change in test conditions, such as might be caused by a corrupt tester bribed to influence the outcome of retests, could cause the probability of passing retests to differ horn the probability of passing the original test. 22 ~ptiom descn~d blow cm 1~t t. my due desired the probabfity with which s~ples of a model tit Me acay typical wodd be judged erroneously, on the basis of retests, to be so atypical as to be unacceptable. Such options require several initial tests to characterize armor deemed typical and acceptable and would be more efficient (req uiring less testing) if the testis one that results in a score rather than a pass or failure. 23 See ~so next Ffi~g, ad app. D (esp. bOX D-1) ~ VO1. 2 of this WWII. ~From 1980 ~ou@ 1990, of 170 us, law e~orcment Offlcem ~U~ w-or, 104 (61 percent) Were killed by head wo~ds. [140]

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Police Body Armor Standards and Testing: Volume I 21 The 10 percent occurrence criterion discussed here for illustration is arbitrary. It would also be reasonable to require ballistic testing only under those conditions that research shows affect ballistic resistance substantially and occur at least, for example, 5 percent of the time. Deciding where to draw the line is a policy choice for NIJ, but requiring testing under conditions that occur no more than 1 percent of the time would be unnecessarily costly and the marginal benefit might not be measurable. Two extreme conditions that have been the subject of recent controversy are exposure of armor to blistering heat and the heavy wetting of armor as a result of immersion, sweating, or rain. Although these conditions apparently are rare, lesser wetting of armor by sweat or rain is common. However, no one knows how frequently untreated fabric armor is wetted enough to degrade its ballistic resistance to some unacceptable level. Test Procedures This section describes OTAS findings regarding controversial aspects of the test procedure specified by NIJ Standard 0101.03: the BFS test (for protection against injury by a stopped bullet), the number of shots required per panel, what non-penetration in testing says about risk of penetration in an assault, the test fixture on which armor is shot, and the prohibition on patting down bulges in the armor caused by previous shots in the test sequence Validity is at issue in all cases; the correspondence of test results to risk in service is uncertain. In some cases, the controversy is compounded by the lack of a clear specification of maximum acceptable risk, as noted above. The impact of a bullet stopped by armor can kill or injure the wearer. Bruising and minor laceration is to be expected, but some test of the ability of armor to protect its wearer from critical injury is needed. The NIJ test, which is based on the depth of the crater made in clay behind the armor when it is hit, serves this purpose. Of the armors that have stopped bullets in assaults, those that would have passed the NIJ test (for protection from a stopped bullet of the type it stopped in an assault impacting at the same speed as in the assault) limited the chance of death or life-threatening injury to about 1 in 300, which is much smaller than the maximum risk acceptable to NILECJ in 1976: 1 in 10. Armor fails the NIJ test if the depth of the crater (called the backface signature, or BFS) made in the clay behind the armor exceeds 44 mm. The 44 mm limit was based in part on NILECJ-sponsored experiments in which animals wearing one type of armor were shot with one type of bullet at a specified nominal velocity. 2526 No Werner of NIJ-certified armor has suffered a type of injury that this test was designed to prevent, even though it was not intended to prevent such injuries with certainty. However, critics in the armor industry contend that soft armor designed to protect wearers from high-energy handgun bullets (type III-A) could be made lighter, more flexible, and more comfortable if the BFS limit were increased or if a resilient backing material were used, and they hypothesize that this could be done without exceeding the NILECJ-specified maximum acceptable risk. Now that hundreds of officers have been shot on their armor and a few thereby injured, it is possible to compare injuries sustained (or lack thereof) to the backface signatures produced in clay behind armor of the type worn, using weapons and cartridges of the types used by their assailants. Such measurements are called reenactments; they are reenactments not of the assault, but of a ballistic test the armor might have been subjected to (see figure 8). Reenactments are a uniquely valuable, ethical tool for investigating the safety guaranteed by the existing NIJ test and for assessing alternative tests. In particular, they could provide the data required to estimate whether the 44-mm BFS limit is more stringent than required to meet the 1976 NILECJ 25 me ~e~emh ~dicat~ 44~a~ ~ ~ppropfiate, if not ~omemative, BFS limit for .qg.speci~ led round-nose bullets impacting at about 8(X) feet per second (a type I threat) on 7-ply Kevlar armor. NILECJ Standard 0101.01 extrapolated the limit to all armors at all ballistic-resistance levels, assuming the BFS limit that would limit the risk from a high-energy bullet stopped by any armor to 10 percent would be no greater, and might be smaller, than the BFS limit for .38-Special bullets on 7-ply Kevlar armor @ster Shubiq pers. comrn., 13 Nov. 1991]. This was a reasonable conjecture at the time. 26 me NJJJ77J ~so ~d~ ~y ~xpefien~ ~ ~hi~h -~r~d goats ~ere. shot with .357 Magnum ~d g-mm b~le~, as Wa armor on clay backing, but the research was not completed or published.

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22 Police Body Armor Standards and Testing: Volume IFigure 8 Reenactment of a Ballistic Test That Armor Shot in an Assault Could Have Been Subjected To assessment Reenactment Anal ysisv .. Assessment of risk of armor passing test of armor failing testSOURCE: Office of Technology Assessment, 1992.safety goals or any other goal NIJ might consider. DuPont had an independent laboratory perform several such reenactments in October 1991. OTAsanalysis (appendix D) of the results (and the fact that only 2 to 4 of the roughly 600 shots stopped by armorcaused serious injury) is the basis for the findingabove. OTAs analysis shed little light on the discrimina-tion of the testi.e., on whether the risk to wearers of armor that would have failed the test was substantially greater than the risk to wearers ofarmor that would have passed the test (see figure 9).To assess the discrimin ation of the test more accurately, more reenactments would have to be performed.Although NDs 44-mm BFS limit has been a topicof considerable controversy, it has not been a majorcause of certification-test failures: as of October 31,1991, less than 3 percent of the models of armor submitted for an NIJ certification test failed solely because of excessive backface signature.27The relationship between the probability of armor penetration on human wearers and the probability of armor penetration in a NIJ test is not known. The probability that a panel of armor will stop a bullet may vary from one location on the panel to another. It may depend on the number of shots that have previously hit the same panel. It may also depend on whether the panel is wet. The fact thateach of four panels has stopped six fair shots in a test only provides information about the geometric mean(a kind of average28) of stopping probabilities averaged over all shot locations and wet/dry conditions. In particular, it allows one to calculate the statistical confidence with which the geometricmean stopping probability exceeds any confidence is for submitted to and tested for certification of model compliance geometric of 24 probabilities is calculated by multiplying them and raising the result (the product) to Power

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Police Body Armor Standard and Testing: Volume I l 23100%1 o%1%o. 1%Figure 9Discrimination of the NIJ Test for Protection From the Impact of Stopped Bullets given FAIL) Perfect Discrimination Confidenceo0.0010.0020.003 given PASS) None 0.004Reenactment data provide 90-percent conf idence that the risk of trauma to wearers of armor that wouldhave passed the test (Pr{trauma, given PASS}) and the risk of trauma to wearers of armor that wouldhave failed the test (Pr{trauma, given FAIL}) are in the shaded region shown. If they were at the upper left-hand corner of the region, the test would have perfect discrimination; if they were at the lowerright-hand corner of the region, the test would have no discrimination. This result indicates thatPr{trauma, given PASS} is less than about 0.0025 unless the test has little discrimination.Whatever the value of Pr{trauma, given FAIL}, if Pr{trauma, given PASS} were at the right-handboundary of the region, there would have been a 90-percent probability that the reenactment results would have led to a greater maximum-likelihood estimate of Pr{trauma, given PASS} than the one actually obtained (0). This is what -percent confidence means.SOURCE: Office of Technology Assessment, 1992.limit of interest.29 30 This information is important for characterizing the reproducibility of test results, but it says nothing about the mean stopping probability on human wearers averaged over shot locations and conditions of assaults.31 That is an issue ofvalidity. The DuPont-sponsored reenactments showed that,in an assault, armor may stop a projectile of a typeit is unlikely to stop in a test. Physical reasoning, andballistic tests sponsored by Allied-Signal, suggest that part of the reason for this apparent discrepancy is that most types of projectiles are more likely to penetrate typical armor if they hit it broadside, as in most shots of the NIJ test, than if they impact at an angle, as often happens in assaults. The backingmaterial used in the test may also make a difference.Performance and analysis of the additional reenactments would yield more information about the For stopping probability were 90 percent, there would be a 92 percent chance that one or more have occurred; thus the geometric-mean stopping probability (on clay) is at least 90 percent with 92 confidence. By the same reasoning, it is at least 95 percent with 71 percent confidence, at least 99 with 21 percent confidence, and at least 99.9 percent with 2 percent confidence.30 shot shots therefore probability is as high as most would want. It provides 75 percent confidence that the stopping probability is at least 50 but only 51 confidence that it is at least 90 and only 2 percent confidence that it is at least 99 percent.31 of 1,o79 on one sample of clay, on another sample of clay, on goat on goat abdomen. data, not yet analyzed, for .357 and .45-caliber threats N. comm., Jan. 10, 1992], but none for human wearers.

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24 Police Body Armor Standards and Testing: Volume I400 300200100 0Figure 10Shots Per Panel in Actual AssaultsAssaults 25 20 15 10 5 0 Saves Slayings 234512345 Shots per PanelSOURCE: DuPont, 1991, based on DuPont and FBI records.correlation of armor penetration on clay with armor penetration on human wearers. This information could be used to determine the number of shots a certification test must have to infer whether the armor limits the probability of penetration to whatever level may be required by policy, with the confidence required. (The probabilities of penetration on clay and in service need not be equal for the test to be valid, but the relationship between them must be known, at least statistically.) Neither the six-shot per panel NIJ .03 test nor the five-shot per panel NIJ .02 or PPAA tests reflect expected assault conditions: in a typical shooting in which an officers armor is hit, only one panel is hit, and by only one shot. The .02, .03, and PPAA tests for soft armor specify five or six shots per panel partly for conservatism (i.e., to simulate a worse-than-expected multi-shot assault) and partly for economy (i.e., they require additional shots on a panel in lieu of shooting them at separate panels, which would increase the cost of testing).In over 90 percent of 440 felonious shootings of armor wearers, only one shot hit the armor. In only two casesless than 0.5 percent-did five shots hita panel. In no case did six shots hit a panel (see figure10). [16]32 To simulate these assaults in terms of shots per panel, a realistic 48-shot test33 would require shooting 23 complete armors,34 about sixtimes as many as the .03 standard requires: two to six(nominally four) complete armors. The realism of NIJ-compliant testing would be improved if the NIJ standard were revised to allow testing of a whole armor garment on a testfixture, such as a mannequin, to which the armorcould be affixed by the strapping or fasteners a wearer would use. Such a revision would alsocreate an incentive for technological innovation. Forexample, stitching elastic strapping directly to the32rhese based on FBI of slayings of armored officers from 1980 through 1989 (fatal wounds occurred outside 426 saves from 1973 through 1989 recorded by Club In there were five saves with an unspecifiednurnberofbullets stopped by one panel and one or two bullets stopped by the opposite panel. Furthermore, of were non-fatally hit on unarmored areas of the body. of shots would the amount of information the test would provide about the ballistic resistance A 48-shot test shots on of panels and one shot on each of 44 panels, requiring and hence 23 armors to be shot.

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Police Body Armor Standard and Testing: Volume I l 25 ballistic panels might reduce ply separation of some armor in an assault as well as in testing, which would improve the reproducibility of test results. NIJ has considered alternatives to the fixture specified in the .03 standard and has had the National Institute of Standards and Technologys Office of Law-Enforcement Standards (NIST/OLES) conduct tests of three alternative fixtures: (1) the clay block specified by NIJ Std. -0l0l.03 in a square frame, (2) a mannequin as specified by PPAA STD-1989-05, [113] and (3) an experimental curvilinear test fixture (called the curv) consisting of a rectangular frame holding a clay block but with semicylindrical sides facilitating the attachment of a complete armor by means of its own strapping and fasteners (see photo). NIJ found the curv to be superior to the .03 block, partly on the grounds that ballistic tests of identical armor showed greater consistency on the curv than on the block. [149] Other advantages of the curve, relative to the clay block, are: (1) the greater realism of testing whole armor attached by its own strapping and fasteners; and (2) the practical necessity of doing so to test an integral armor garment (e.g., one made with a single, -wrap-around, non-removable ballistic element). A mannequin of the type specified by PPAA would also have these advantages. 35 As noted above, NIJ recently directed H.P. White Laboratory, Inc., to use the curvilinear test fixture for tests of model compliance withNIJ Standard O101.03. However, the standard itself was not changed, so other testers may continue to use the clay block specified by the standard. Requiring adjustment (patting down) of armor between shots would control shot-to-shot and test-to-test variability of test conditions. For armor susceptible to ply separation, this would decrease the stringency of the test but would more realistically simulate typical assaults, in which one panel of armor is hit by only one bullet. It might simulate assaults with multiple hits per panel less realistically. Ballistic tests of identica1 36 armor panels indicate that ply separation contributes to the penetration probability of some types of armor, especially unquilted fabric armor. Patting the armor down between successive shots (to reduce or eliminate ply separation, push the armor against the backing, and smooth the backing) reduced the penetration probability and hence also the stringency of the test and the variance in penetrations (a measure of shot-toshot differences) .37 Some critics of the NIJ standard argue that ply separation (bunching or balling) does not occur in actual assaults and that it should therefore be corrected in certification tests by patting the armor down between shots. Most of the evidence adduced consists of statements by survivors of shootings, who claim their armor did not bunch up, or that they recall that their armor did not bunch up, or that they do not recall their armor bunching up. 38 Some critics theorize that the dynamic, elastic human torso oscillates after being shot and pats the armor down from the inside. Clearly the chest or abdomen, after being indented by a stopped bullet, does return to its pre-impact position (unless the stopped bullet fractures a bone or the armor penetrates the skin). However, biomechanical research 35 w ~so fo~d the Cm to be superior to the PPAA mannequin. In these tests, the face of the clay in tie mannequins box was planed to facilitate accurate measurement of the baclcface signature. When armor was mounted on the clay, it arched over the clay in the box, and was not in intimate contact with the clay as required by both NIJ Std. 0101.03 and PPAL4 STD-1989-05. NIST noted this may have contributed to ply separation, hence to penetration and variance in results. OTA believes this is not an appropriate compariso~ nor is it consistent with provisions in NIJ Std. 0101.03 for testing of type III or IV ballistic resistance or female models of armor; those provisions, like PPAA STD-1989-05, require clay to be mounded behind the armor panel to assure the panel is in intimate contact with the clay. BFS measurement would be most accurate if the first shot impacts a flat area of the clay, but this need not include the whole face of the clay block. 36 That is, -or pmels made to be as nearly identical as the manufacturing and quality-assurances processes permitt~. ST Here we assume the probability of penehation on any shot is less than one-half, as it is with high cotildence in dlllost ~ c~lcation tests. Otherwise, reducing the penetration probability would increase the variance. 38 The reliabfity of such assertions is doubti. We do not doubt the integrity and conviction of those who make such statements, but considerable psychological research shows that recollection of inconsequential circumstances surrounding a threatening or traumatic event is frequently mistaken. For example, research. with Air Force flight-crew members confirms that even highly-trained people become poor observers under stress. The actual threat that brought on the stress response, having been highly significant at the time, can be remembered; but memory for other details such as clothing and colors is not as clear . [30]

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26 l Police Body Armor Standards and Testing: Volume IMounting Fixtures for Ballistic Tests of Body ArmorTop left: Clay block specified by NIJ Std. 0101.03 in rectangular frame.SOURCE: El. du Pent de Neymours & Co., Inc., 1992.Top right: Mannequin with clay-filled cavity specified by PPAASTD-1989-05.SOURCE: Office of Technology Assessment, 1991.Bottom right: Experimental curvilinear frame tested at HPWLI by NIST/OLES for NIJ.SOURCE: Office of Technology Assessment, 1991.

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Police Body Armor Standards and Testing: Volume I l 27 suggests that the sternum (breast bone) would do so slowly and would not rebound outward. 39 On balance, this is too little information to decide conclusively how common and marked ply separation is in multi-shot assaults. Worse, we know of no ethical means of finding out, so the controversy may continue indefinitely. Even so, it would be reasonable to revise the standard to require patting, with the rationale that the revised test would more realistically simulate the most common type of assaultassaults with one impact per panelbut would fire several such shots at each panel in the interest of economy. Whether to trade off conservatism about rare assaults for greater realism in simulating typical assaults is a policy choice for NIJ. There is no technical reason not to. Assuring Quality NIJs certification procedure certifies adequacy of design. It does not assure product quality, nor does it prevent fraud in the marketplace. It attests that a few samples of each NIJcertified model did pass a test specified by the NIJ standard and implies other samples could also pass the test if constructed in the same manner as the original samples. But certification provides no assurance that they are so constructed. Clearly, assuring product quality would require selecting samples of production armor periodically and testing the samples. It would also require using statistical methods to estimate the probability that the units not tested would pass the test; if it is too low, certification would be denied, suspended, or revoked. OTA has considered two approaches in detail: (1) lot sampling and acceptance testing and (2) statistical process control. These are described below, under Options for the Department of Justice, and in greater detail in appendix E. UNRESOLVED ISSUES More research will be needed to assess the discrimination of NIJs test for protection from the impact of a stopped bullet, to estimate the BFS limit appropriate for whatever safety goal NIJ may specify, or to identify a test with better discrimination between reliable and unreliable armor. Clearly (see Findings) armor that would have passed the test has limited the chance of injury by a stopped bullet of the type, and at the velocity, used in the test, to less than 1 in 300-but so has armor that would have failed the test. Possibly the test discrimin ates poorlyi.e., the risk of trauma to wearers of armor that would have failed the test may differ little from the risk of trauma to wearers of armor that would have passed the test; if so, the allegation of some manufacturers that the test has little discrimination would be borne out. To decide whether this is so would require performance and analysis of additional reenactments. Data from additional reenactments could shed light on other issues related to protection from stopped bullets. They could be used to estimate (1) how risk (in aggregate and by threat) would vary if the BFS limit were varied and (2) the BFS limit appropriate for whatever safety goal NIJ may specify. If additional reenactments are conducted, it would be convenient to measure, at the same time, quantities other than crater depth (e.g., crater diameter); this could allow a test with better discrimination to be identified (see next option). Tests based on crater depth and other measurements (e.g., crater diameter or deformation velocity or pressure) should predict acceptable protection from stopped bullets more reliably than does the current test, which is based on crater depth alone. More measurements would provide more information; further research could compare the cost-effectiveness of tests based on different sets of measurements. For example, the Army developed (for NILECJ) a method to predict the lethality of a stopped bullet based on the bullets mass and velocity, the armors weight per unit area, the wearers weight and body-wall thickness, and the diameter of the crater made by the armor in clay backing. With some adjustment (and, ideally, validation by reenactments), the method could be used to gauge protection from a stopped bullet for armor certification. Very likely, other models based on the same or additional measurements would be even 39A bi~~eC~c~mOdel &SCfi~d ~ ~pp. c ~re~cts tit he stem~ (br~st bone) wo~d not rebo~d outw~d ~ycmd its prt3-klpaCt dkfUlCt2 flDIIl the spine, and it would take about 50 milliseconds-the interval between successive shotsofaMAC-11 submachine gun-for the compression caused by a stopped bullet to subside to 37 percent of the maximum compression. The abdomen would probably take longer.

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28 Police Body Armor Standards and Testing: Volume I more reliable, but research would be needed to confirm this. 40 Untreated fabric armor without waterproof covers is apparently rarely wetted in service (by perspiration, precipitation, or immersion) to the extent that its ballistic resistance is clearly degraded; however, the frequency of such wetting is not known. Hence, if the NIJ standard were amended to make wet-testing optional (as critics propose), we do not know how much greater risk an officer would face wearing dry-certified armor than wearing wet-certified armor. Nor do we know how much more frequently the officer would wear dry-certified armor than wetcertified armor. We suspect the answers to both questions depend on climate, type of duty, and individual physiology, and we expect individuals or departments could answer them as well as OTA or NIJ could. They could measure wetting of their armor by weighing it. However, they would require assistance-training, instructional materials, or worksheetsto estimate the probabilities of wearing and wetting and to understand the uncertainties in the estimates. The status qu0--certification of armor only if samples pass the test after being sprayedguards against the possibility that armor may become dangerously wetted. However, critics of the NIJ standard question the need for the wet testing, arguing that waterproofing causes more trouble than its worth, because it gives the wearer a rubber-sheet effect, making the body armor too uncomfortable to wear. 41 [120] Defenders of the standard point to the profuse sweating that wearing any vest can cause in hot weather, and to the possibility of immersion, as exemplified by an assault in which an officer 42 was held underwater by an assailant who attempted to drown him and then shot him twice in the back, on his armor, with his own revolver. 43 Even in this case, it is not known whether the armor was wet, or how wet it was, where the bullets hit. If such wetting occurred as much as 5 percent or 10 percent of the time, it would very likely have caused penetrations, in assaults, of uncertified, non-wet-tested armor, which in fact has saved hundreds of police officers and not once been penetrated by a bullet it was advertised to stop. 44 No one denies that fabric armor not treated to repel water loses some ballistic resistance as its 45 However, it fully recovers water content increases. its resistance after drying. Soaking such armor may degrade ballistic resistance dramatically; spraying it with salt water to simulate sweating had a negligible effect in one series of tests; [105, 106, 8] we do not know how spraying as spectified by NIJ Standard 0101.03 affects the ballistic resistance of various armors. Tests conducted for NIJ by MSTs Law Enforcement Standards Laboratory in 1990 showed the V 5O (the velocity at which bullets have a 50 percent chance of penetrating) of Kevlar R panels decreased with increasing water content as shown in figure 11. [62] To use this information (or similar information about other bullets or armor) to assess the risk of unacceptable degradation of ballistic resistance, one would have to know the statistics of moisture pickup by armor worn by the wearer or wearers of interest. In an experiment conducted at the FBI Academy, untreated Kevlar R armor worn by an instructor performing prolonged strenuous activity (on a hot, humid day [62]) absorbed and retained perspira40 See appen~ E for further details. 41 FabriC -or tit pasSa a teSt @ cm ~ made t. pass it wet by treating @ b~istic fabric or the fiber from which it is woveQ by eIICIOSklg the ballistic element ina waterproof cover, or by using more layers of untreated fabric. Some treatments may make the armor more costly or less comfortable. 42 Ohio State Trooper Cardinal. 43 Th e me I 8.ply Kevl~ b~k p~el of the officers Point Blank armor (which had a ~ W frOnt pRUel) stopped ~th shots> even fiough m impacted close to the edge of the ballistic panel, where armor is not tested for ballistic resistance. The shots made a hole extending horn 13/d inch to 33/ A inch from the edge of the c~er g~ents pocket for the ballistic panel. The ammunition ww Cm 125-gK JSp .38 SP1 +P. 44 Unmrtified armor not designed to provide rated performan ce when soaked is credited with more saves per vest sold than comparable certifkd (wet-tested) armor is. Mr. ClintonE. Davis, Executive Vice-President, Second Chance Body Armor, Inc., wrote, Ourrecords show over the last eighteen (18) years that 10 percent of the non-waterproofed vests in the field have accounted for 40 percent of the saves. This means that a non-waterproof concealable vest is six (6) times more likely to be worn. [46] OTA is not persuaded of the last poin~ because non-wet-tested armor has been on the market and in service about six years longer than wet-tested armor has, allowing more opportunities for more saves. However, it is plausible that a non-waterproof concealable vest is more likely to be worn. 45 Sowg does not cause ~or ~de from nonwoven Spectra Shie@ composite mtefi to lose bd.listic resistance.

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Police Body Armor Standard and Testing: Volume I l 29Figure 1 lEffect of Wetness on Ballistic Resistanceof KevlarR Armorv50 (ft/s)1,600 1,4001,200 1,000 800 600 400 200 0 20-ply panel+ 12-ply panel0%5%10% 15% 20% 25% 30% 35% 40%Water content (o/o of dry weight) 124-gr 9mm FMJSOURCE: Office of Technology Assessment, 1992, based on data from NIST/LESL, 1990.tion equalling 22 percent of its weight, which couldcause a considerable loss of ballistic resistance (seefig. 11). [8] If ballistic resistance is to be certified even for such conditions of heavy and prolonged perspiration, spraying or immersing the armor before ballistic testing is necessary. However, some perhaps most-duties will not cause enough perspi-ration to significantly degrade the ballistic resistanceof untreated fabric armor,46 and moisture pickup may depend on fabric47 and individual physiology. By wearing and weighing untreated fabric armor, an individual could estimate how often it becomes dangerously wet. By alternately wearing waterproof armor, he or she could decide whether it is lesscomfortable; if not, there would be no reason to wearthe untreated armor. However, we doubt many officers would conduct such an experiment at their own expense, and what they learn would not helpothers.NIJ could solicit volunteers for a similar nationwide experiment and provide them with armor. For the results to be useful in various jurisdictions, NIJ would have to determine how wetting and wear rate (or comfort) depend on various factors, such as theambient (outdoor) Temperature-Humidity Index andwhether the wearer spends most of the time in a climate-controlled environment. One of the problems of such a study would be reliance on volunteers; those who do not volunteer may be the ones most sensitive to comfort-the ones hypothetically most benefited by untreated armor.Departments that order and enforce the wearing ofarmor would be in a position to randomly selectsubjects and order them to participate. However, thedepartment would face an ethical dilemma: could itjustify ordering an officer to stop wearing wet-testedarmor and instead wear untreated armor for the duration of the experiment, knowing there is apossibility it might be wetted enough to be degradedand then shot in that condition? The risk appears low, but such an experiment must be performed to measure it. It may happen that the risk is more than offset by the increase in wear rate. A decision to do so would be analogous to a common one: deciding to issue type II or II-A armor rather than type III-A armor, because of comfort, economy, or expected wear rate; the type III-A armor promises betterprotection.In summary, there is an apparently small but unquantified risk that non-wet-tested armor might be wetted enough to be degraded and then shot.However, wet-tested armor might be worn less oftenthan non-wet-tested armor. There is no compelling evidence that requiring wet-testing costs more lives than it saves, but neither is there a compellingrationale for continuing to require armor to be testedwet, as the current NIJ standard does. Revising the NIJ standard to allow armor to be tested wet or dry would allow purchasers to choose armor that they believe offers the most protection, considering wear rate as well as ballistic resistance, and considering local and personal factors, such as climate and typeof duty. They might err, and more research would beneeded to give them better guidance.OPTIONS FOR THE DEPARTMENT OF JUSTICESome have questioned the need for a Federal rolein the formulation of standards for body armor intended for use by State and local police officers,yet no serious contention has surrounded the assign-ment of that role-given that it should existto the46 Up percent fabric holds less water than does saturated

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30 Police Body Armor Standards and Testing: Volume I Department of Justice. 48 Within the Department of Justice, the role again finds a natural home: the National Institute of Justice, created in 1979 by the Justice System Improvement Act. NIJs mission is to encourage research and development to improve the criminal justice system and to disseminate the results to Federal, State, and local agencies. [144] A major part of NIJs effort to assist lawenforcement agencies with the acquisition of new technology is the issuance of voluntary standards for a variety of police equipment, including radios, weapons, automobile tires, and body armor. The Office of Law-Enforcement Standards (OLES) of the National Institute of Standards and Technology (NIST) assists NIJ in developing and revising standards, including the standard for ballistic resistance of body armor. Although no significant body of opinion holds that the body armor question lies outside of NIJs mandate or purview, many have expressed the feeling that NIJ has become unduly wedded to the existing standard. They feel that long-standing conflict over the body-armor issue among persons whose strong personalities and knowledgeable minds are driven by the earnest desire to save the lives of as many police officers as possible has solidified positions, especially those in NIJ, to a degree beyond that justifiable on purely scientific or technical grounds. This perception constitutes a public relations problem for NIJ. It is clear the standard should be revised eventually. It could be revised now to reduce the latitude in test procedures permitted by the standard. This would limit lab-to-lab and test-to-test variations in test conditions, which might be partly responsible for variations in test results. Minor variation in test conditions occurs in normal testing; its influence may be minor or insignificant. However, it is possible a tester may have some incentive to conduct a test by the book but in a manner intended to maximiz e (or, depending on the incentive, to minimize) the probability that the armor will pass the test. Minor revisions in the standard could limit the latitude of such inadvertent or operatorcontrolled variation in test conditions. The section Revise NIJ Standard 0101.03 (below) describes several such revisions; they include specifications of bullets and backing material, reducing the range of allowed backing-material temperature, measuring backing-material temperature and consistency more frequently, and patting down armor between test shots. Revising the standard to specify a number of specific procedures already used at H.P. White Laboratory, Inc. would further limit possible lab-tolab variations in test conditions. (Recall that any individual with two guns, modelling clay, a thermometer, a steel ball, and a ballistic chronograph can test samples of armor and certify the models compliance with the NIJ standard on the labels of other units of the model.) Moreover, as discussed above in Findings, the validity of the current test has not been demonstratednor can it be until acceptable risks are specified. This lack of demonstrated validity does not require revising the current standard. But if NIJ wishes to assure purchasers and wearers of the protection afforded by a unit of certified armor, it must (1) specify its safety goals so the validity of the current test or a proposed revision maybe tested; (2) test the validity of the test specified by the standard; (3) revise the standard, if required for validity, and (4) implement a quality-assurance program to ensure that certifiled armor offered for sale is as safe as the samples that passed the (valid) test of ballistic resistance. All the items on this list are discussed in the next four subsections: Specify Acceptable Risks, Revise NIJ Standard 0101.03, Assure Quality, and Sponsor Research. Specify Acceptable Risks Specifying acceptable risks would allow the validity of the current test to be decided scientifically and would give NIJ a yardstick for assessing options for revising its test and its certification process. NIJ should specify the types and degrees of injuries and incapacitation by penetrating and nonpenetrating bullets that the armor is to prevent and the maximum acceptable risks of such injuries and incapacitation (as well as the statistical confidence with which acceptable risk must be demonstrated). Illustrative options for doing so are listed below. Safety goals should be weighed carefully, bearing in mind they benefit only those who wear certified armor. Making the goals extremely stringent could decrease the number of such officers and increase the ranks of those who wear uncertified ~ See, however, Other Policy options, below, regarding the jurisdictions of the Federal Trade Commission (FTC) md the OCCupatiOMl safeW and Health Administration (OSHA).

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Police Body Armor Standards and Testing: Volume I l 31 armor or none. Requiring very high confidence that the test limits the probability of whatever type of injury is to be avoided to a very small number will make the cost of testing the validity of the test very high and will increase the cost of compliance testing and of producing certified armor. It may also require armor to be thick, stiff, and heavy in order to have a reasonable chance of passing the test. Such armor would probably be worn less, which could cost lives, on balance. A statement of goals could be of the following generic form: Certified armor should: (1) Stop each shot, up to n per panel, with probability p s or greater. (2) Leave wearer ambulatory with no injury rated higher than ion the Abbreviated Injury Scale 49 [88] after each stopped shot, with probability p a or greater. Reenactments or other tests should: (3) Demonstrate that armor meeting the certification criteria will accomplish goal (1) with at least Cl-percent confidence and goal (2) with at least C 2 -percent confidence. Customizing this statement requires choosing values of n, p s i, p a and C. The parameters n and p s specify the required protection from penetration in an assault by whatever projectile may be specified: n is the number of shots the ballistic element (e.g., panel) is to withstand, and p s is the minimum reliability with which each of them is to be stopped. Thus if a panel is to stop each of six shots (n = 6) with 97 percent reliability (p s = 0.97), then it should stop all six shots with 83 percent reliability (0.97 6 = 0.83). A ballistic test used or proposed for certification of armors ballistic resistance may require more or fewer than n shots per panel. Whether it provides the protection required by this safety criterion (viz., from n shots per panel) is a question of validity that can only be settled (ethically) by reenactments designed to test the validity of the test. If the safety criterion requires the armor to withstand more impacts of the specified bullet per panel than have ever hit a panel of armor in service, the validity of the test cannot be tested scientifically. If there are enough assaults of the appropriate type to perform reenactments and test validity, the conclusion may depend on the required reliability, and will depend on the confidence (C 1 ) with which validity is to be demonstrated. Requiring extreme reliability and confidence will ensure that any ballistic test will fail a test of validity. If NIJ wants a demonstrably valid test, it must not require that a panel withstand more than a few shots, nor that it withstand them with 100 percent reliability, nor that this be demonstrated with 100 percent confidence. The parameters i and p a specify the required protection from stopped projectiles in an assault. The parameter i designates the maximum tolerable severity of injury, on the following scale: Abbreviated Injury Scale 6: fatal 5: critical-survival uncertain 4: severe, life-threatening-survival probable 3: severe, not life-threatening O-2: not severe Protection from incapacitation may also be specified-for example: Leave wearer ambulatory. . It is tempting to specify Leave wearer ambulatory and able to hit a man-sized target in a vital area with at least one round from service weapon (etc. ), but it would be difficult or impossible to demonstrate scientifically that a ballistic test meets such a requirement. The ability to walk awaya useful capability in itself-is more easily tested and can be considered a proxy (a plausible substitute) for other desirable capabilities, the validity of which may be impossible to confirm. The parameter, is, again, a kind of reliability the reliability of protection from severe injury or incapacitation by a stopped bullet. More of it is better, but the higher the value specified, the lower the confidence with which reenactments can confirm validity. Requiring extreme reliability (p a ) and confidence (C 2 ) will ensure that any ballistic test will fail a test of validity. The illustrative generic safety goals are necessarily technical in order to make it possible to test their validity scientifically. Even if realistic parameter values are chosen, it may take years before a test of 49we expect ~ ~~~d ~mt -or t. ~mvent ~jfies ~~ MS rafigs of 6 (fa@), 5 (criti~: surviv~ uncertain), and 4 (severe, life-~atellirlg: survival probable) with a high probability. NIJ could allow injuries rated 3 (severe, not life-threatening) or below on the AIS, on the grounds that requiring armor to prevent them may have a negative, but as yet unquantiiled, effect on wear rate.

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32 Police Body Armor Standards and Testing: Volume ITable 3Choices for Safety GoalsOption PsiPac1C2Rationale160.97 3 0.99 5099Goals defined implicitly by NIJStandard 0101 .03@ c260.95 3 0.95 9595 NIST hypothesized ps,-d to bal-ance risks, pa, C1/1 OO, andC2/100 assumed equal.e360.90 3 0.95 9595Less than half of penetrating torso wounds are fatal.fNotes: not higher injury rating, 4, which is to be avoided, means severe, life-threatening;surviva! probable.bNIJ requires, probability day at least 97 percent, for soft armor. The calculation, based on the test of 24 fair shots per caliberwith no penetrations, is: 1thus 0.50= 1-0.971524. The standard is also consistent with (Cl = 0.71), and other combinations. However, the refers to the probability on wearers, in service. This is tacitly assumed to be comparable to the stopping probability on clay, but additional research would be needed to test the hypothesis. implicitly required safety from stopped bullets is greater than required by the as discussed above in Findings. illustrative boundary between bad and marginai armor (see appendix forthe fact that the of increased O percent to 5 percent, the acceptable risk of life-threatening injury from a stopped bullet has been decreased from10 percent (the to 5 percent. fThe ailowed risk (1of penetration is twice the risk (1of iife-threatening injury by a stopped bullet, because fewer than half of penetrating torso wounds are This may risks more than option 2. SOURCE: Office of Technology Assessment, 1992.the validity of a ballistic test with respect to the goalsmay be completed. They will have to be explained in terms familiar to police officers. The present question for NIJ is whether to specify safety goals explicitly and realistically enough so they can be used as a standard against which the validity of ballistic tests of armor can be assessed. Table 3 shows three possible combinations ofparameters for the generic statement of safety goals and provides a brief rationale for each option. All arerealistic and, we believe, comparable in some ways to what NIJ Standard 0101.03 was intended torequire. However, these options are more rigorous inthat they specify confidence levels with which validity is to be demonstrated. It is harder to demonstrate that a ballistic test meets a safety goalrequiring only 97 percent reliability in stopping each shot and 50 percent confidence that the reliability isthat high than to demonstrate that the test meets adifferent safety goal requiring 100 percent reliability in stopping each shot but no specific confidence thatthe reliability is that high.Revise NIJ Standard 0101.03This section describes the most important optionsfor revising NIJ Standard 0101.03. Appendix E discusses these (and others) in greater detail. Whatever other changes are made, some of thelatitude in test procedures permitted by the standard should be reduced to limit lab-to-lab and test-to-testvariations in test conditions, which might be partly responsible for variations in test results. Since NIJ Standard 0101.03 was issued in 1987, the White Laboratory, Inc. (HPWLI), which currently is the only ballistic test laboratory authorized by NIJ to do testing for certification by NIJof compliance withthe standard, has adopted particular ways of con-ducting the test in the interest of reproducibility. NIJ has also issued directives instructing the H.P. WhiteLaboratory to perform parts of the test in particular ways that are not the only ways allowed by thestandard. Other laboratories attempting to conduct atest in accordance with the standard+. g., for developmental testing of a new modelmightconduct their testing in accordance with the standardbut not exactly in accordance with the procedures H.P. White Laboratory would use for certification testing of the model. The lab-to-lab variations in test conditions might cause lab-to-lab variations in test results. To preclude this, when NIJ does revise NIJ Standard 0101.03, the many de facto requirements that have been specified by letters, telephone calls, or established practice at H.P. White Laboratory should be incorporated explicitly into the revised standard. This would limit the ways in which test conditions

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Police Body Armor Standard and Testing: Volume I l 33 could differ from laboratory to laboratory, and, at laboratories other than H.P. White, from test to test. Revise the Backface Signature Limit The backface signature limit specified by the standard could be revised based on the maximum risk of injury NIJ will accept and the statistical confidence it requires in the validity of the BFS test. The amount of each demanded is a policy choice for NIJ (see Specify Acceptable Risks, above). Of all possible limits that would satisfy the safety goals, NIJ could choose the one that maximizes discriminationi.e., that minimizes the estimated probability of misclassification of acceptably safe armor as unacceptable or vice versa. 50 The maximum allowable BFS might be calculable from existing reenactment results, depending on the safety goals. For example, if NIJ chooses to allow at most a 1 percent probability of life-threatening injury from a stopped bullet (even if survival is probable), then permitting any BFS but prohibiting penetration would accomplish this with better than 99 percent confidence, if armor designs and the firearms threat change no more than they did in the past two decades. Additional research would be necessary to determine BFS limits appropriate for some safety goals NIH might specify (e.g., if NIJ undertakes to protect wearers against injuries rated 3 or lower on the Abbreviated Injury Scale). Require Patting Down of Armor Between Shots The standard could be revised to require patting down of armor between shots. This would simulate typical assaults (those that cause only one impact per panel) more realistically than does the current test. However, it might simulate assaults causing multiple impacts per panel less realistically. It would limit inadvertent shot-to-shot and test-to-test variability of test conditions, and would limit opportunities for any operator (tester) to deliberately influence the probability of passing by aiming either at or between the hills caused by the bunching effects of previous shots. It would decrease the stringency of the test in that it would give armor of models susceptible to ply separation in testing an increased probability of passing. Specify Standard Bullets The bullets to be used in the test could be specified more precisely. The probability with which a commercially available bullet of specified mass and caliber will penetrate armor at a specified velocity depends on the bullets construction and composition. [28] A bullet that deforms may be stopped by relatively few layers of armor; many more layers may be needed to stop sharp fragments of a hard or steel-jacketed bullet. Specifying more precisely the bullets to be used in the test could increase reproducibility of test results. It would not simulate the diversity of the threat faced by police officers (neither does the current set of test bullets), but reenactments could assess the reliability with which armor tested with standard bullets stops bullets that hit wearers. Specify Standard Backing Material The backing material to be used could be specified. Specifying the backing material to be used for the test might improve its reproducibility. In practice, only one backing material, Roma Plastilina No. 1 modeling clay, is used by HPWLI for NIJ certification tests. However, NIJ Standard 0101.03 does not require it; a tester may use any material that passes the drop test specified to check the consistency of the backing material. Some backing materials conditioned to pass the drop test yield different backface signatures at the much higher deformation velocities typical of a ballistic test conducted in accordance with NIJ Standard 0101.03. 51 Thus the drop test does not assure that backface signatures produced in different backing materials behind similar armors by similar bullets impacting at similar velocities will be the same. Some materials are known to yield different results; others, not yet tested by NIJ or NIST, could differ more dramatically. Specification of a backing material would eliminate this potential source of 50 ~temtively, ND could choose the one that minimizes its expected utility, [9] but this would involve assessing the value of a life saved in monettuy or other terms to which the values of other possible benefits and losses may be compared. This has proven controversial in other fields, such as automotive safety engineering. [76] 51 For exmple, ~ teSt5 conducted b y the British police Scientific Development Branc& under otherwise simih COnditiOKIS the average (Vk fitt@ backface signatures produced in U.S.-made Plastilioa and U.K.-made Plasticize were similar at impact velocities of 350 Ws but differed by about 4.4 mm for each 100 m/s above or below 350 m/s. [29] Cf. [28, 84].

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34 l Police Body Armor Standards and Testing: Volume I variation in-or operator influence ontest conditions. 52 Reduce Tolerances on Backing Material Properties The allowable range of backing material temperature could be reduced, and the temperature or consistency of the backing material (or both) could he required to be measured at specified time intervals or stages of ballistic testing. The consistency (flowability) of clays commonly used for backing has been shown to be very sensitive to clay temperature. Variation in the temperature of clay backing material could make the difference between passing and failing NIJs test for protection from stopped bullets. In 1977, the Aerospace Corporation recommended that, for adequate reproducibility, backing material be maintained at 70 plus or minus 2F. NIJ Standard 0101.03 allows backing material to have a temperature between 15 and 30C (59 and 86F) during testing. It requires the consistency of the material to be tested three times by dropping a specified weight from a specified height and measuring the depth of the crater it makes. In practice (at the H.P. White Laboratory), all three drop tests are conducted beforenot during or after-testing. Possibly the consistency may change during testing, e.g., as a result of bullet impacts or as the materials temperature approaches ambient temperature (which is required to be in a narrower range than the materials temperature). In tests observed by OTA, the backing material cooled during testing. 53 Possibly this happens in a uniform way at H.P. White, but it could vary from lab to lab. Moreover, the latitude permitted by the standard could be exploited to influence test results. Reducing the allowable range of backing material temperature, and requiring temperature to be measured and consistency to be tested at specified time intervals or stages of ballistic testing would limit the latitude for deliberate or inadvertent variation of test conditions, even within the bounds allowed by the standard, or inadvertent transgression of the bounds. It may improve the reproducibility of backface signature measurements, especially of crater diameter, which could be used in assessing protection from blunt trauma. It might also improve reproducibility of penetration tests. Certify Wet and Dry Ballistic Resistance Separately The wet test could be mandatory or optional. Some purchasers or wearers may prefer armor with inadequate wet ballistic resistance because of cost or comfort. They may suspect the risk of its becoming dangerously wet is so low they would accept it. But to learn what the risk is, they would have to weigh their armor regularly to measure and record water retention and analyze the records to calculate frequency with which retention exceeds dangerous levels. In compensation, wear rate might be increased among those who find armor with inadequate wet ballistic resistance more affordable or comfortable but who also value NIJs certification. Subjecting armor only to the dry testing specified in the NIJ standard would reduce the stringency of the test, even for armor that performs as well wet as dry. If NIJ wished to compensate for this and maintain the stringency of the test, it could offer a choice of the current wet-dry test or a double-dry test with the same number of fair shots required. To halve the cost of testing, one industry source has proposed testing and certifying dry ballistic resistance or wet ballistic resistance, but not requiring both tests. This is based on the premise that no conceivable type of armor has less ballistic resistance when dry than when wet. This is plausible, but even if true, armor would have a higher probability of passing a wet-only test than a wet-dry test with twice as many shots. Rate the Ballistic Resistance of Each Certified Model With a Score The standard could specify a way to rate the ballistic resistance of each certified model with a score, such as the V 50 ballistic limit-the velocity at which test bullets have a 50 percent chance of penetrating. The present certification test is a pass/fail test, although armor may be tested for resistance to any type of bullet at any velocity. Nevertheless, knowing 52 ~~ou@ ~~y ~ompoSition d~ons~ably ~=. me r~~ts of the deformation test (for protection from nollpenetrating blllle~), it k IIOt ~~ that it affects the results of the penetration test. More research would be needed to fmd out whether it does. 53 However, after the last shot at each panel, craters were filled with clay warmer than the rest of the face of the clay block.

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Police Body Armor Standards and Testing: Volume I l 35Figure 12Estimates of V5O and V1O Obtained by Logistic RegressionPenetration probability10.9 Logistic Model Data (stop)0.8 Data (penetration)0.7 0.6V50 estimation0.5 -0.4 0.3 0.2 V10estimation 0.1 0 600700 800 9001,0001,1001,200 1,300 1,400 Impact velocity (ft/s)1,500 1,600 .357 Magnum at 30 incidence v. panel on clay, smoothed between shots.SOURCE: Office of Technology Assessment, 1991.only that a model has passed does not indicate the velocity at which the test bullets would be expected to penetrate it. Indeed, that velocity cannot beestimated unless the test requires some test bullets toimpact at a velocity high enough to penetrate the armor samples. A test developed by the Department of Defense [138] for estimating the V5Oof (unbacked) armor could replace NIJs current test of resistance to penetration.54 A model could be certified to have a specified type or level of ballistic resistance if the V50 for each type of test bullet equals or exceeds aspecifiedminimum value, and if samples also pass a test for protection from blunt trauma. But the model would be rated as well as certified, to let purchasers know the model exceeds minimum NIJ standards-and by how much. An alternative score is the V1O, the velocity at which test bullets have a 10 percent chance of penetrating-i.e., at which armor stops a bullet with 90 percent reliability. It could be estimated by logistic regression [91] based on velocities andpenetrations measured in a DoD-like test (see figure12). For purchasers who demand 90 percent, ratherthan 50 percent, reliability in stopping, the V1O wouldbe more appropriate for comparing to typical or conservative threat velocities than would the V50. However, probability of penetration in service may differ from probability of penetration in the test. A samples V05 or V01 could likewise be estimated by logistic regression, and certification could be based on them. However, there would be more uncertainty in these estimates than in estimates of Vl0 or V50; achieving comparable accuracy would require firing more shots than would be needed to estimate V10 or (esp.) V50. Use Anthropomorphic Test FixtureThe standard could be revised to allow or requiretesting of a whole armor garment on an anthropo-morphic test fixture to which the armor could beaffixed by the strapping or fasteners a wearer woulduse. This would improve the realism of the test and would be necessary to test integral armor-armor made from a single panel of ballistic material stitched so that it can not be spread flat on a clay block. The curvilinear frame developed and tested by NIST for NIJ would be a suitable fixture; so DOD as backing material, but NIJ could that clay or some other backing material be used. Regardless used, calibration of penetration probability in the test with penetration probability in assaults would be an issue.

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36 l Police Body Armor Standards and Testing: Volume I would the mannequin specified by the PPAA. For either fixture-but especially for the mannequin-it would be prudent to require aim points to be at least 2 inches from the frame or clay box walls, to limit whatever effects their proximity may have on penetration probability or deformation. The standard should continue to require that the armor be placed in intimate contact with the backing material. This may require mounding the backing material behind some parts of some armors. However, the standard could require the backing surface to be flat within a specified (perhaps threatdependent) radius about the first aim point, to permit backface signature to be measured to the current standard of accuracy. The standard could specify test fixtures of various sizes to accommodate armors of various sizes. NIJ Standard 0101.03 specifies that samples be sized for 46to 48-inch chests, explaining that the larger the size, the more likelihood that all ballistic testing will fit on just two complete armors. However, it may be that smaller armor is less likely to pass the test, other things being equalthat is, size may be ballistically significant. We do not know whether it is, and we do not know that it is not, but qualitative physical arguments suggest that it might be. 55 Hence a more conservative provision would require separate certification, and hence testing, of each size, which might require fixtures of several different sizes. This would be costlyit would increase the nonrec urring cost to the test lab, which would have to stock several fixtures, and the recurring cost to manufacturers, who would have to conduct more testing. A simpler, less costly, and even more conservative option would be to require the samples to be the smallest size in which the model is offered. Certification of lots (rather than models) as described below would require the test lab to have fixtures of various sizes to accommodate samples of various sizes. However, it would not require each size of each model represented in a lot to be tested; two tests per lot would suffice in some cases. Assure Quality OTA found (see Findings above) NJs certification procedure. does not assure product quality, nor does it prevent fraud in the marketplace. This section describes briefly two options, either or both of which NIJ could implement if it wants to assure buyers and wearers that each unit of armor certified to comply with the current NIJ standard (or a successor) and offered for sale has been subjected to sampling for inspection and ballistic testing to confirm its adequacy or its similarity to samples previously found to be adequate. Many variants of these illustrative options maybe invented; they would provide different types of guarantees-some statistical, others non-quantitative. They would assure product quality and provide assurance against some imaginable types of fraud in the marketplace. Preventing false or deceptive labeling or advertising is discussed below, under Other Policy Options. Certify Lots NIJ could certify lots, rather than models, of armor. This would certify acceptability of product quality, not just acceptability of model design. If intentional or inadvertent changes in manufacturing caused the ballistic resistance of units (nominally) of a certain model to degrade, this option would keep lots with unacceptably low ballistic resistance off the market, with a probability that can be made as high as desired by testing a sufficient number of samples per lot. Either the ballistic test specified in NIJ Standard 0101.03 or a different one could be used. To exercise this option, NIJ would have to 1. 2. 3. Define a lot. Specify a sampling plan--i.e., the number of samples from each lot to be tested, and criteria for acceptance and rejection based on test results. Ensure the samples to be tested are selected randomly from each lot. 55 men -or stops a btile~ tie armor is bent stretched, and often cut or tomnea the point of impact. A second shot may be more Wely to Penetrate ifit impacts in the damaged area than if it impacts eLsewhere. The standards requirement that each test shot impact at least 2 away inches from any point of prior impact is intended to prevent this influence. However, the radius of weakening might extend farther than 2 inches from a point of impact; the extent of weakening would depend on the bullet its velocity, the armor, and the backing material.

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Police Body Armor Standard and Testing: Volume I l 37Figure 13Notional Control Chart for Sequential Lot-Acceptance TestingFailures7I/ 4--3-2-1Consumers risk if accepted lot -. >---Producers risk if rejected lot 23 4 67 8910TestsSOURCE: Office of Technology Assessment, 1992.Any of several sampling plans could be used.56 Asequential procedure that OTA finds appropriatelll l l lis based on a pass/fail ballistic test for individ-ual units;57allows a lot to be inhomogeneous;58defines a unit as bad if it has a probability of passing less than a value pb to be specified byNIJ;defines a unit as good if it has a probability of passing greater than a value pG to bespecified by NIJ; limits the probability of accepting a lot contain-ing one or more bad units to the maximum consumers risk acceptable to NIJ; andI.i.rNIJs the probability of rejecting a lot contain-ing only good units to the maximum producers risk acceptable to NIJ.59Samples would be selected randomly from the lotand tested. Testing could be allowed to continueuntil the fraction of tests failed is so great that the lotmust be rejected to limit the consumers risk or so small that the lot must be accepted to limit the producers risk. To decide when a lot must be accepted or rejected, a control chart, such as the one shown in figure 13, could be used.60Establish a Voluntary Quality-Control ProgramNIJ could establish and supervise a voluntaryquality control program analogous to the Listing orClassification programs of Underwriters Laborato-ries, Inc. (UL). UL Classification of a model of armor would be based partly on ballistic testing of samples and partly on inspection of the manufacturers manufacturing and quality assurance processes by NIJ or a contractor.56 However, some Widely used may be inappropriate-for example, those that assume a defective unit identified as such by inspection or testing. .03 test could be used, if armor were only tested wet, so that one unit of would be for each test.58 whether have some other approaches quality control, it is important that a lot be homogeneous, i.e., that units in the lot be alike, at least insofar as can be determined before testing.59 accomplished the ballistic E of vol. 2 for details.

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38 Police Body Armor Standards and Testing: Volume I The cost of UL or UL-like procedures for assuring body armor quality would depend on how samples are selected, the standard to which they are tested, and the confidence (if any) with which the tests are to assure that the samples are identical to the original test articles or, in any case, provide the ballistic resistance required. A simple option would be Classification of a model of armor as compliant with NIJ Standard 0101.03 or a similar standard. This would require iNIJial testing of samples in accordance with the standard. Continuation of Classification would be contingent on audits of the manufacturers production and quality control processes and on selection, inspection, and ballistic testing of production samples to gauge their similarity to the iNIJial samples. UL estimates iNIJial testing of a model could be performed for about $3,000, with each additional model (from the same manufacturer) tested at the same time costing about $1,500. Ongoing FollowUp Service would require four annual visits and cost little more than about $700 to $1,000 per year, if the manufacturers quality control program is in good order. [112] However, this option would not provide quantitative estimates of the maximum risk of UL-Classified armor. Moreover, some manufacturers might hesitate to participate in it because they would perceive unannounced factory inspections as being intolerably intrusive. Sponsor Research Some OTA findings noted gaps in the knowledge needed for rational standard-setting that could be filled by additional research. For example, one noted that the relationship between the probability of armor penetration on human wearers and the probability of armor penetration in an NIJ test is not known. OTA also noted two Unresolved Issues that might be resolved by further research: More research will be needed to assess the discrimination of NIJs test for protection from the impact of a stopped bullet, to estimate the BFS limit appropriate for whatever safety goal NIJ may specify, or to identify a test with better discrimination between reliable and unreliable armor. Tests based on crater depth and other measurements should predict acceptable protection from stopped bullets more reliably than does the current test, which is based on crater depth alone. Further research could compare the cost-effectiveness of tests based on different sets of measurements. The following options for research are aimed at reducing or eliminating these gaps in knowledge. NIJ could propose, through the budget process, a specific program of research for funding by Congress (see Legislative Options, below). Investigate Resilient Backing Material NIJ could investigate the use of resilient backing material for penetration testing. Use of resilient backing material, such as foam rubber or silicone rubber, for penetration testing might make ply separation and penetration probability during testing comparable to that in an actual assault. However, there is little objective information about how much ply separation occurs in any shootings of armored humans, especially in assaults, and we doubt there is an ethical way of le arning much more about it. The correlation of penetration in assaults with penetration on resilient backing in tests could be estimated by conducting reenactments of assaults (see below). The current BFS measurement on clay backing or some other test (see below) could be used to estimate risk of injury from stopped bullets. Sponsor Additional Reenactments of Assaults NIJ could sponsor additional reenactments o f assaults for any or all of several purposes, for example: l l To estimate the risk, and confidence limits on the risk, of injury by stopped bullets, as a function of backface signature depth. Additional reenactments would allow the dependence of risk of injury (especially minor injury) on backface signature to be inferred with greater statistical confidence than has been possible based on the limited number of reenactments performed to date. To estimate confidence limits on the risk of injury by stopped bullets, as a function of backface signature diameter or measurements other than backface signature. These might predict serious injury more reliably than does backface signature diameter. The Army developed a procedure for predicting risk of lethality as a function of backface signature diameter, but it is based on animal data and should be validated, if possible, using human data; we expect adjustment will be required.

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Police Body Armor Standards and Testing: Volume I l 39 To infer a relationship between the probability that armor will be penetrated on clay backing material in a test and the probability that similar armor will be penetrated in an actual assault. To infer relationships between the probabilities of armor penetration on backing materials other than clay and the probability that similar armor will be penetrated in an assault. Penetration in assaults may correlate better with penetration on a resilient backing material such as foam rubber or silicone rubber than on modeling clay. Develop Parametric Models of Mortality and Morbidity From Stopped Bullets NIJcould develop parametric models of mortality and morbidity from stopped bulletsmathematical formulae or graphs that predict the probabilities that a single nonpenetrating shot would kill or cause unacceptable trauma, based on parameters that describe the threat (bullet mass and velocity), the armor (areal density), ballistic test results (BFS), and the wearer (e.g., weight). The model could be fit to data from reenactments of shootings of armored humans, or, using a different procedure, to data from the experimental shooting of animals. Limits on BFS depth or diameter could be based on the model, the maximum acceptable risk specified by policy, and the parameters describing the threat, the armor, and the wearer. An advantage of using such models as a basis for certification is that assessment of the protection new types of armor provide against various threats would not require additional biomedical tests (i.e., shooting large mamm als, and killing some); it would only require additional ballistic tests: shooting the armor of interest with bullets of interest at velocities of interest, using a backing such as clay. This would be more complicated and cumbersome than the current procedure. On the other hand, it would provide a rationale for certification of protection against trauma caused by bullets other than Type I bullets stopped by armor other than 7-ply Kevlar armor. It also would allow armor to be certified for use only by wearers large enough to face only an acceptable risk; smaller wearers are probably at greater risk than larger wearers in similar (but larger) armor. Sponsor Research on Tests for Protection From Stopped Bullets NIJ could sponsor research on the practicality and validity of tests for protection from stopped bullets based on measurements other than backface signatures. Some experts speculate that measurements of pressure in backing material behind armor during impacts of test bullets might predict serious blunt trauma more reliably than BFS depths do. There is a plausible argument-but as yet no proofthat backing pressure may be a better predictor of certain functional injuries of the heart (e.g., ventricular fibrillation or block) that can be caused by blunt impacts. In experimental animals, such injuries correlate with backing velocity times deformation (a viscous criterion), which can be reconstructed from measurements of backing acceleration during impact. Research on such correlations and on measurement techniques has been conducted, and continues, at General Motors Research Laboratories and abroad, in England, France, and Germany (see app. E). However, more research is needed to correlate measurements of each type with various types of injuries to various vital organs. As with the BFS criterion, validation will ultimately require reenactments of assaults on humans. Appendix E discusses other options for the Department of Justice. OTHER POLICY OPTIONS The Federal Trade Commission (FTC) and the Occupational Safety and Health Administration (OSHA) have jurisdiction in some matters related to body armor: the FTC has authority to prosecute cases of false or deceptive advertising or labeling, 61 such as the incorrect labeling of armor as an NIJ-cert~led model, and has done so. OSHA could protect the occupational safety of police officers by requiring them to wear approved armor under specified conditions, but has not done so. Expand FTC Activities; Involve OSHA The Administration could direct FTC or OSHA to expand activities within its jurisdiction related to body armor. For example, if further complaints of false or deceptive advertising or labeling are alleged, 61 &-.e tie Feder~ Trade Co~SSion ACt (38 S~t.717, ~~ amended (15 USC. 41.58)); tie Clayton Act (38 stat.730, as amended (15 U.S.C. 27)), and the Federal Trade Commission Improvements Act of 1980 (94 Stat. 374-397).

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40 l Police Body Armor Standards and Testing: Volume I investigation and prosecution are within FTCs jurisdiction. NIJ must play a role because inspection of samples for conformance with those submitted for certification testing will require access to the submitted samples archived by NIJs Technology Assessment Program Information Center (TAPIC). If the Administration desired to mandate the wearing of approved armor on duty, OSHA has the authority to do S 0 62 This would require collaboration by OSHA, which has experience in and infrastructure for regulation, and NIJ and NIST, which have expertise in the standardization and testing of body armor. LEGISLATIVE OPTIONS Fund NIJ-Sponsored Research Congress could authorize and appropriate funding for NIJ-sponsored research on topics cited above in Options for the Department of Justice: l l l l l Investigation of resilient backing for penetration testing. Reenactments of actual assaults, to test the validity of the current test for blunt-trauma protection or help design a new one. Measurement of backing pressure or acceleration in reenactments, and correlation with blunt trauma in assaults. Development of a logistic model that predicts the incidence and severity of trauma from stopped bullets, as a function of multiple measurements, to be used as a basis for armor certification; also Periodically updating such a model using data from reenactments. Enact H.R. 322, the Police Protection Act of 1991 Congress could enact H.R. 322, the Police Protection Act of 1991, which would prohibit sale of armor not certified to comply with the current NIJ standard or any future revision thereof, and would authorize NIJ to enforce this ban. Thereafter Congress could fund the mandated program of NIJ regulation. This would be a sweeping change. It would give NIJ more authority and responsibility, the discharge of which would require more resources-i. e., funding. Authorizing legislation should consider possible conflicts of jurisdiction, especially with OSHA. If OSHA undertook to require police officers to wear OSHA-approved armor, and if OSHA-approved armor were not NIJ-certified, a legal conflict would arise. However, OSHA has not expressed an intent to protect police by such a measure. Enacting H.R. 322 would not settle the standards controversy and might exacerbate it. We do not know whether the Act would save more lives than the current regime of voluntary compliance with the NIJ standard. Purchasers could have confidence that armor sold after the law was in force would be very safe, as NIJ-certified armor is now. The question is whether it would be purchased and worn as much as some non-NIJ-certiiled armor, which some customers prefer because of comfort or cost. We do not know the answer to this question, but it should not be dismissed; uncertified armor has also performed well in service and has saved many lives. Enacting H.R. 322 would require manufacturers to submit representative samples of certified models of armor to NIJ periodically to be tested for continued compliance. That is, H.R. 322 would create a mandatory quality-control program. It does not specify details of the sampling and testing; it leaves that to NIJ. NIJ has not yet proposed or specified details, so it is not yet possible to assess the effectiveness of the quality-control provisions of the bill. Enacting H.R. 322 is not necessary to assure consumers that production units of NIJ-certified models conform to the units submitted for certification or have acceptable ballistic resistance. A voluntary quality-control program would suffice for that. Fund Expanded FTC Activity Congress could fund expanded FTC activity to investigate complaints of, and prosecute cases of, false or deceptive advertising or labeling of armor. This may be necessary if complaints increase--e.g., if more vigorous enforcement by NIJ uncovers more evidence of such malfeasance. Fund an OSHA program To Standardize Armor and Mandate Wearing Congress could fund an OSHA program to standardize armor and mandate wearing. The Administration could propose such a program, or the Congress could require the Administration to do so. @Occupatio~ Safe@ and Health Act of 1970,29 U.S.C. 651 et seq.

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Police Body Armor Standards and Testing: Volume I 41 OSHA has the authority to specify standards for armor and require police officers (or others) engaged in hazardous duty to wear OSHA-approved armor. OSHA has expressed no intent to do so. This measure would be even more sweeping than enacting H.R. 322 (which would not mandate wearing of armor), and it would probably be more controversial. However, if enforced vigorously, it could increase wear rate and save more lives. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10, 11. BIBLIOGRAPHY Better Bugs for Biotech-Spider Silk, Symbionts, and Seaweed, Biotechnology, vol. 7, October 1989, p. 993. Premium Rifle Ammunition: Is It Worth the Extra Cost?, Gun Tests, February, 1990, vol. II, No. 2, pp. 13-16. Confirmation Time: The Excellent Consistency of Kevlar (R) Aramid Fiber, Section 12 of The DuPont Mid-West Body Armor Symposium, sponsored by Missouri Police Chiefs, Inc., and International Association of Chiefs of Police, Chesterfield, MO, 29-31 Aug. 1990 (Wilmington, DE: The DuPont Co., 1990). Biting the Bullet: New Nonwoven Finding Application in Ballistic Protection, Nonwovens Industry, April 1991, pp. 28 & 30. SACOP Mid-Year Conference a Resounding Success, The Police Chief, August 1991, p. 86. [Published by the International Association of Chiefs of Police.] Woman Injured in Jetliner Test, New York Times, 31 Oct. 1991, p. A23, column 1. Aerospace Corp., Law Enforcement and Telecommunications Division, Equipment Systems Improvement Program Find Report Body Armor Field Test and Evaluation, Volume I.--Executive Summary, Aerospace Report No. ATR-77(7921)-2 (Washington, DC: The Aerospace Corp., September 1977). Aerospace Corp., Law Enforcement and Telecommunications Division, Equipment Systems Improvement Program Final Report Body Armor Field Test and Evaluation, Volume 11.Test And Evaluation, Aerospace Report No. ATR-77(7921)-2, (Washington, DC: The Aerospace Corp., September 1977). Anderson, J.A., Separate Sample Logistic Discrimination, Biometrika, vol. 59,1972, pp. 19-35. Anderson, J.A., Logistic Discrimination, pp. 169-191 in P.R. Krishnaiah and L.N. Kanal (eds), Handbook of Statistics, vol. 2 (New York, NY: North-Holland, 1982). Apostolakis, George, The Concept of Probability in Safety Assessments of Technological Systems, Science, vol. 250,7 Dec. 1990, pp. 1359-1354. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. Ayoob, Massad, NIJ-Backed HR-4830: Police Protection Act or Cop-Killer Bill? The New Gun Week, June 29, 1990, pp. 1 &5. Bachner, [Thomas E.] Ed, The History of NIJs Test Problems, section 9 of The DuPont Mid-West Body Armor Symposium, sponsored by Missouri Police Chiefs, Inc., and the International Association of Chiefs of Police, Chesterfield, Missouri, August 29-31, 1990 (Wilmington, DE: The DuPont Company, 1990). Bachner, Thomas E. (Ed) Jr., (Ballistics Account Manager, DuPont), personal communication, 14 June 1991. Bachner, Thomas E. (Ed) Jr., Brierly, William, and Slavin, Helen A., Casualties vs. Casualty ReductionLessons Learned From the Eighties, section 7 of The DuPont Mid-West Body Armor Symposium, sponsored by Missouri Police Chiefs, Inc., and International Association of Chiefs of Police, Chesterfield, MO, 29-31 August 1990 (Wilmington, DE: The DuPont Co., 1990). Bachner, Thomas E. (Ed) Jr., Slavin, Helen A., and Brierly, Chief William (Ret.), Casualty Reduction Analysis presentation, Lancaster, PA, 17 Apr. 1991. Bachner, Thomas E. (Ed) Jr., Slavin, Helen A., and Brierly, William, Casualty Reduction Analysis, 5th cd., briefing charts, unpublished, 11 June 1991. Bachner, Thomas E. (Ed) Jr., Slavin, Helen A., and Brierly, Chief William (Ret.) (DuPont Officer Safety Team), Casualty Reduction Analysis, briefing charts, unpublished, December 1991. Birnbaum, Z.W., and Tingey, F.H., One-sided Confidence Contours for Probability Distribution Functions, Annals of Mathematical Statistics, vol. 22, 1951, pp. 592-596. Bowen, I.G., et al., Biophysical Mechanisms and Scaling Procedures Applicable in Assessing Responses of the Thorax Energised by Air-blast Overpressures or by Nonpenetrating Missiles, Annals of the New York Academy of Science, vol. 152, 1968, p. 122 ff. Brand Consulting Group, Understanding the Police Officers Attitudes, Perceptions, and Behavior Toward Soft Body Armor of Kevlar (South field, MI: The Brand Consulting Group, October 1986). Brand Consulting Group, Police Managements Attitudes, Perceptions, and Behavior Toward Soft Body Armor (Southfield, MI: The Brand Consulting Group, March 1987). Brand Consulting Group, Police Officer Evaluation of Soft Body Armor Made of Kevlar #129 (Southfield, MI: The Brand Consulting Group, September 1988). Brand Consulting Group, A Quantitative Assessment of Attitudes Toward The Body Armor Stand-

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42 Police Body Armor Standards and Testing: Volume I 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. ards Controversy for E.I duPont de Nemours & Company, Wilmington, Delaware (South field, MI The Brand Consulting Group, July 1990). Brand, Milton I., Critical Factors in the Decision to Wear Body Armor, section 5 of The DuPont Mid-West Body Armor Symposium, sponsored by Missouri Police Chiefs, Inc., and International Association of Chiefs of Police, Chesterfield, MO, 29-31 Aug. 1990 (Wilmington, DE: The DuPont co., 1990). Breslow, N.E., and Day, N. E., Statistical Methods in Cancer Research, vol. 1: The Analysis of CaseControl Studies (Lyon, France: IARC, 1980). Breslow, N.E. and Powers, W., Are There T WO Logistic Regressions for Retrospective Studies?, Biometrics, vol. 34, 1978, pp. 100-106. Brown, Eric, Home Office Ballistic Standards, pp. 127-142 in L. Tobin (cd.), op. cit. infra. Brown, Eric (Head, Firearms and Armour Programme, U.K. Home Office Police Scientific Development Branch), personal communication, 29 Nov. 1991. Buckhout, Robert, Eyewitness Testimony, Scientific American, vol. 231, no. 6, December 1974, pp. 23-31 and 166 (bibliography). Burington, Richard Stevens and May, Donald Curtis Jr., Handbook of Probability and Statistics with Tab/es, Second Edition (New York NY: McGraw-Hill, Inc., 1970). Caplan, Marc H. (Technical Manager), and Valdez, Richard A. (Project Director, NIJ TAPIC), letter to Mr. Richard C. Davis (President, Second Chance Body Armor), Nov. 30, 1990. Carroll, Andrew W., and Soderstrom, Carl A., A New Nonpenetrating Ballistic Injury, Annals of Surgery, vol. 186, no. 6, December 1978, pp. 753-757. Cascarano, Paul (Assistant Director, NIJ), Body Armor Manufacturers Memorandum #6. .SUBJECT: Use of Curvilinear Fixture for Body Armor Testing, 27 April 1992, with attachment. Clare, Victor R., Lewis, James H., Mickiewicz, Alexander P., and Sturdivan, Larry M., Blunt Trauma Data Correlation, Technical Report no. EB-TR-75016, (Aberdeen Proving Ground, MD: Edgewood Arsenal, May 1975); NTIS AD-A012 761. Cochran, William G., Annals of Mathematical Statistics, vol. 23, pp. 315-345, 1952. Cohen, Samuel H., Presser, Robert A., King, Abram, and Desper, C. Richard, Analysis of Ballistically Caused Damage in Some Test Panel Fibers (Natick, MA: U.S. Army Natick Research, Development, and Engineering Center, May 1991). Cooper, G.J., and Taylor, D.E.M., Biophysics of Impact Injury to the Chest and Abdomen, Journal 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. of the Royal Army Medical Corps, vol. 135, 1989, pp. 58-67. Cork, C.R., The Application of the BPI Test in a Research Environment, pp. 5-24 in L. Tobin (cd.), op. cit. infra. Cox, D.R., The Analysis of Binary Data (London, England: Methuen, 1970). Cox, D.R., and Hinkley, D. V., Theoretical Statistics (London, England: Chapman& Hall, 1974). Cox, D.R., and Snell, E.J., Analysis of Binary Data, 2nd ed. (New York, NY: Chapman and Hall, 1989). Damm, R.B.D., Lungzeitverhalten von Schutzwesten, Polizei-Fhrungsakademie, Forschungsund Entwickhmgsstelle fr Polizeitechnik, Mai 1988. Damm, R.B.D., Long-Term Behavior of Protective Vests, Police-Leadership Academy, Research and Development Center for Police Technology, May 1988, English translation by James A. Worthey, dated 12 June 1990. Darling, D.A., The Kolmogorov-Smirnov, Cramrvon Mises Tests, Annals of Mathematical Statistics, vol. 28, 1957, pp. 823-838. Davis, Clinton E. ( Executive Vice-President, Second Chance Body Armor, Inc.), letter to Michael B. Callaham (OTA), 18 Nov. 1991. Davis, Richard C. (Inventor), Bullet Proof Protective Armor and Method of Making Same, U.S. Patent 3,783,449,8 Jan. 1974 (filed 8 May 1972). Davis, Richard C. (Inventor), Bulletproof Protective Body Armor, U.S. Patent 3,829,899,20 Aug. 1974 (filed 31 Oct. 1973). Davis, Richard C. (Inventor), Bullet Resistant Under Garment, U.S. Patent 3,855,632, 24 Dec. 1974 (filed 7 Jan. 1974). Davis, Richard C. (Inventor), Bullet Proof Protective Armor, U.S. Patent 3,894,472, 15 July 1975 (filed 8 Aug. 1973). Day, N.E., and Byar, D.P., Testing Hypotheses in Case-Control Studies-Equivalence of MantelHaenszel Statistics and Logit Score Tests, Biometrics, vol. 35, 1979, pp. 623-630. Day, N.E., and Kerridge, D.F., A General Maximum Likelihood Disc riminant, Biometrics, vol. 23, no. 2, June 1967, pp. 313-323. Dean, Bashford, Helmets and Body Armor in Modern Warfare (New Haven, CT: Yale University Press, 1920). Di Maio, Vincent, Gunshot Wounds (New York NY: Elsevier, 1985). Dunn, Donald (President, HPWLI), personal communication (fax), 7 June 1991. Dunn, Donald (President, HPWLI), personal communication (fax), 7 November 1991. Dunn, Donald (President, HPWLI), personal communication (telephone conversation), 7 Nov. 1991

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Police Body Armor Standards and Testing: Volume I l 43 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. Dunn, Donald (President, HPWLI), personal communication (telephone conversation), 8 Nov. 1991 Eberhardt, Keith R., National Institute of Standards and Technology, Statistical Engineering Division, Presentation to TAPAC Subcommittee on Weapons and Protective Systems, Reston, Virginia, February 13, 1990, unpublished, prepared 6 Mar. 1990, with minor corrections added 19 Apr. 1990. Eberhardt, Keith R., National Institute of Standards and Technology, Nature of Acceptance Sampling, unpublished, dated 24 Apr. 1991; presented to OTA 19 July 1991. Efron, Bradley, and Tibshirani, Robert, Statistical Data Analysis in the Computer Age, Science, vol. 253,26 July 1991, pp. 390-395. Eliason, Lawrence K. (Chief, Law Enforcement Standards Laboratory), Subject: Ballistic Limit of Kevlar (R) When Wet, Memorandum for Lester D. Shubin (Director, Science and Technology, National Institute of Justice), July 17, 1990 (unpublished). Fackler, Martin L., Wound Ballistics-A Review of Common Misconceptions, Journal of the American Medical Association, vol. 259, no. 18, May 13, 1988, pp. 2730-2736. Fackler, Martin L., The Ideal Police Bullet, Internal Security and Co-In No. 2, pp. 45-46; Supplement to International Defense Review, no. 11/1990, 1990. Fallon, John E. (Director, Industrial Products Division, Fibers Department, du.pent), Miner, Louis H. (Research Associate, dupont) and Bachner, Thomas E. Jr. (Ballistics Account Manager, duPont), Inconsistent NIJ /03 Body Armor Test Results, copies of transparencies presented to the National Institute of Justice, 29 Sept. 1989. Feighan, Rep. Edward F. (Co-Sponsor), Police Protection Act of 1991, H.R. 322, introduced in 102d Congress, 1st session, 3 Jan. 1991; cosponsored by Rep. Moakley. Fieller, E. C., Some Problems in Interval Estimation, Journal of the Royal Statistical Society B, vol. 16, 1954, pp. 175-185. Frank, Daniel E., Testing of Commercial Body Armor Under NIJ Standard-0101 .03, pp. 161-175 in L. Tobin (cd.), op. cit. infra. Frank, Daniel E. (Program Manager, Weapons and Protective Systems, Office of Law-Enforcement Standards, National Institute of Standards and Technology), personal communication, 12 Sept. 1991. Frost, Lerinda Luecking, and Brus, John, GMRs Viscous Criterion Impacts Safety Research, Search, vol. 26, no. 2, May 1991. [Published by General Motors Research Laboratories, Warren, MI; cites work by Viano & Lau.] 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. Garfield, Richard M., RN, DrPH, and Neugut, Alfred I., MD Ph.D., Epidemiologic Analysis of Warfare: A Historical View, Journal of the American Medical Association, vol. 266, no. 5, 7 Aug. 1991, pp. 688-692. Gibbons, Jean Dickinson, Fishers Exact Test, pp. 118-121 in Encyclopedia of Statistical Sciences (Samuel Kotz & Norman L. Johnson, eds.), vol. 3 (New York NY: John Wiley & Sons, 1983). Gigerenzer, Gerd, et al., The Empire of Chance (Cambridge, England: The University Press, 1989). Goldfarb $ Michael A., M.D., MAJ, MC; Ciurej, Terrence F., M.D., CPT, MC; Weinstein, Michael A., M.D., MAJ, MC; and Metker, Le Roy W., B.A., A Method for Soft Body Armor Evaluation: Medical Assessment, Technical Report EB-TR-74073 (Aberdeen Proving Ground, MD:: Edgewood Arsenal, January 1975). NTIS accession number AD/A-005 575. Goldfarb, Michael A. M.D., MAJ, MC; Ciurej, Terrence F. M.D., CPT, MC; Weinstein, Michael A. M.D., MAJ, MC; and Metker, Le Roy W., B.A., Body Armor Medical Assessment (Washington, DC: U.S. Department of Justice, Law Enforcement Assistance Administration, National Institute of Law Enforcement and Criminal Justice, May 1976). Graham, John D., and Vaupel, James W., Value of a Life: What Difference Does It Make?, Risk Analysis, vol. 1, no. 1, 1981, pp. 89-95. Haag, Lucien C., Ballistic Gelatin: Controlling Variances in Preparation and a Suggested Method for the Calibration of Gelatin Blocks, AFT E Journal [Association of Firearm and Tool Mark Examiners], vol. 21, no. 3, July 1989, pp. 483-489. Hoffman, Mark S. (cd.), The World Alamanac and Book of Facts 1990 (New York, NY: Pharos Books, 1989). Hogan, Harry, Gun Control, Issue Brief IB89093 (Washington, DC: Library of Congress, Congressional Research Service, Government Division, September 9, 1991). Howson, Colin, and Urbach, Peter, Scientific Reasoning: The Bayesian Approach (La Salle, IL: Open Court, 1989) Howson, Colin, and Urbach, Peter, Bayesian Reasoning in Science, Nature, vol. 350, pp. 371-374,4 April 1991. H.P. White Laboratories, Inc., NIJ-STD-0101.03 Verbal and Letter Modifications, unpublished, October 1989. IACP/BJA [International Association of Chiefs of Police/Bureau of Justice Assistance] National Law Enforcement Policy Center, Body Armor, Concepts and Issues Paper (Arlington, VA: IACP/BJA National Law Enforcement Policy Center, June 1, 1990).

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44 Police Body Armor Standards and Testing: Volume I 84. 85. 86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96. Iremonger, M.J., and Bell, S.J., Simulation of Behind-Armour Trauma, pp. 191-204 in L. Tobin (ed.), op. cit. infra. Jarrett, William S. (cd.), Shooters Bible, no. 83, 1992 Edition (Hackensack, NJ: Stoeger Publishing co., 1991). Jason, Alexander, and Fackler, Martin L., M.D., Body Armor Standards--A Review and Analysis, Final Report, Second edition (Pinole, CA: Center for Ballistic Analysis, 1990). Jason, Alexander, and Fackler, Martin L., M.D., Body Armor Standards: A Review and Analysis, Wound Ballistics Review, Journal of the International Wound Ballistics Association, Winter/91, pp. 14-37. Joint Committee of the American Medical Assoc., American Assoc. for Automotive Medicine, and the Society of Automotive Engineers, The Abbreviated Injury Scale (AIS)-1976 Revision, (Morton Grove, IL: American Assoc. for Automotive Medicine, 1976). Kaswell, Ernest R., Textile Fibers, Yarns, and Fabrics (New York, NY: Reinhold, 1953). King, Albert I. and Viano, David C., BaseballRelated Chest Impact, Final Report to CPSC, Contract # CPSC-C-84-1170, July 15, 1986. Koch Gary G., and Edwards, Suzanne, Logistic Regression, pp. 128-133 in Encyclopedia of Statistical Sciences (Samuel Kotz & Norman L. Johnson, eds.), vol. 5 (New York, NY: John Wiley & Sons, 1985). Kroell, Charles K., Thoracic Response to Blunt Frontal Loading, The Human Thorax--Anatomy, Injury and Biomechanics, Proocedings P-67, (Warrendale, PA: Society of Automotive Engineers, 1976), pp. 49-78. Laible, Roy C. (cd.), Ballistic Materials and Penetration Mechanics (New York, NY: Elsevier Scientific Publishing Co., 1980). Lau, Ian V., and Viano, David C., How and When Blunt Injury Occurs-Implications to Frontal and Side Impact Protection, pp. 81-100 in SAE proceedings P-215: Proceedings of the 32nd Stapp Car Crash Conference, Atlanta, GA, October 1719, 1988; reprinted as SAE Technical Paper 881714. Lindley, D.V., The Use of Probability Statements, pp. 25-57 in C.A. Clarotti and D.V. Lindley, eds., Accelerated Life Testing and Experts Opinions in Reliability, Proceedings of the International School of Physics Enrico Fermi, Course CII (New York, NY: North-Holland, 1988). Lininger, L., et al., Comparison of Four Tests for Equality of Survival Curves in the Presence of Stratification and Censoring, Biometrikia, vol. 63, 1979, pp. 419-428. 97. 98. 99. 100. 101. 102. 103. 104. 105. 106. Mantel, N., and Haenszel, W., Statistical Aspects of the Analysis of Data from Retrospective Studies of Disease, Journal of the National Cancer Institute, vol. 22, 1959, pp. 719-748. Marano-Goyco, Joan, Fuel Fire Test Facility Testing of Spectra Shield Bullet Reststant Vests, report number NADC-0041-60 (Warminster, PA: Naval Air Development Center, February 1990); Distribution Authorized to U.S. Government Agencies and Their Contractors; Critical Technology; February 1990. Other Requests for This Document shall be refered [sic] to COMNAVAIRDEVCEN. McIlhenny, Candace (Project Director, NIJ TAPIC), letter to Mr. Donald Dunn, H.P. White Laboratory, Inc., 27 April 1992, with enclosures. Metker, LeRoy W., et al. A Method for Determining Backface Signatures of Soft Body Armors, Tech. Rep. EB-TR-75029 (Aberdeen Proving Ground, MD: U.S. Army Armament Research and Development Command, May 1975); DTIC ADA012 797. Metker, LeRoy W., Prather, R.N., Coon, P.A., Swann, C.L., Hopkins, C.E., and Sacco, W.J., A Method of Soft Body Armor Evaluation: Cardiac Testing, Tech. Rep. ARCSL-TR-78034 (Aberdeen Proving Ground, MD: U.S. Army Armament Research and Development Command, Chemical Systems Laboratory, November 1978); NTIS accession number AD-A063 522. Michaels, Maureen (Strategy Polling Corporation), Rowan, Michael (Strategy Polling Corporation), and Curran, Jim (John Jay College of Criminal Justice), National Body Armor Survey (New York NY: City University of New York, John Jay College of c riminal Justice, March 1991). Miner, Louis H., Analysis of Current Technologies, Allied-Signal Spectra 1000 and SpectraShield and KEVLAR (R) aramid, for Soft Body Armor, (Wilmington, DE: E.I. dupont de Neymours & Co., Inc., June 1989). Montanarelli, Nicholas, Hawkins, Clarence H., Goldfarb, Michael A., and Cuirej, Terrence F., Protective Garments for Public Officials LWL-TR30B73 (Aberdeen Proving Ground, MD: U.S. Army Land Warfare Labortory, August 1973); NTIS AD-A089 163. Montanarelli, Nicholas, and Hawkins, Clarence E., Lightweight Body Armor for Law Enforcement Officers, report EB-SR-75001 (Aberdeen Proving Ground, MD: Edgewood Arsenal, March 1975). Montanarelli, Nicholas, Hawkins, Clarence E., and Shubin, D.Lester D., Body Armor--Lightweight Body Armor for Law Enforcement Officers (Washington, DC: U.S. Department of Justice, Law Enforcement Assistance Administration, National Institute of Law Enforcement and Criminal Justice, May 1976).

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Police Body Armor Standards and Testing: Volume I l 45 107. 108. 109. 110. 111. 112. 113. 114. 115. 116. 117. 118. 119. 120. 121. Montgomery, D. C., Introduction to Statistical Quality Control (New York NY: Wiley, 1985). Morris, Bunny (FBI Uniform Crime Reporting Program), personal communication, 15 July 1991. Neathery, R.F., et al., Prediction of Thoracic Injury from Dummy Responses, SAEPaper751151, in Proceedings of the Nineteenth Stapp Car Crash Conference, Book P-62 (Warrendale, PA: Society of Automotive Engineers, 1975), pp. 295-316. Neathery, R.F., and Lobdell, T.E., Mechanical Simulation of Human Thorax Under Impact, SAE paper 730982 (Society of Automotive Engineers, 1973). Neathery, Raymond F., Analysis of Chest Impact Response Data and Scaled Performance Recommendations, SAE paper 741188, in Proceedings of the Eighteenth Stapp Car Crash Conference, Ann Arbor, MI, 1974 (Warrendale, PA: Society of Automotive Engineers, 1974), pp. 459493. Papier, Isaac (Managing Engineer, Burglary Detection and Signaling Dept., Underwriters Laboratories, Inc.), personal communication, 9 March 1992. Personal Protective Armor Association (PPAA), Testing Standards for Ballistic Resistance of Personal Body Armor, STD-1989-05, 22 June 1989. Prather, Russell N., Swann, Conrad L., and Hawkins, Clarence E., Backface Signatures of Soft Body Armors and the Associated Trauma Effects, Technical Report no. ARCSL-TR-77055, (Aberdeen Proving Ground, MD: U.S. Army Aberdeen Proving Ground, Chemical Systems Laboratory, November 1977). NTIS accession number AD-A049 463. Prather, Russell (USA BRL), personal communication, Apr. 22, 1991. Press, S. James, Bayesian Statistics: Principles, Models, and Applications (New York, NY: John Wiley & Sons, 1989). Read, Campbell B., Fiellers Theorem, pp. 86-88 in Encyclopedia of Statistical Sciences (Samuel Kotz & Norman L. Johnson, eds.), vol. 3 (New York, NY: John Wiley & Sons, 1983). Rae, Calyarnpudi Radhakrishna, Linear Statistical Inference and Its Applications, 2d ed. (New York, NY: John Wiley & Sons, 1973). Rowan, Michael, Comparative Analysis of the 1977 Aerospace Study and the 1990 John Jay College of Criminal Justice/Strategy Polling Corporation Soft Body Armor Survey, 9 Nov. 1991 (unpublished). Second Chance Body Armor, Inc., Second Chance Saves (Central Lake, MI: Second Chance Body Armor, Inc., undated). Second Chance Body Armor, Inc., Second Chance vs. Magnum Force (Central Lake, MI: Second Chance Body Armor, undated). [VHS videocassette] 122. 123. 124. 125. 126. 127. 128. 129. 130. 131. 132. 133. 134. 135. 136. Sellier, Karl, und Wehner, Heinz, Biologische Toleranzgrenze Bei Schssen Auf Schutzwestentrger, mss, undated. Sellier, Karl, and Wehner, Heinz, Biological Tolerance Limits in the Shooting of Protective Vest Wearers, an English translation by James A. Worthey, dated 12 June 1990, of an undated German manuscript. Siegel, Sidney, and Castellan, N. John Jr., Nonparametric Statistics for the Behavioral Sciences, 2d ed. (New York NY: McGraw-Hill, 1988). Society of Automotive Engineers, Latex Foam Rubbers, SAE Standard J17 JAN85 (Warrendale, PA: Society of Automotive Engineers, 1985). Society of Automotive Engineers, Spongeand Expanded Cellular-Rubber Products, SAE Standard J18 AUG88 (Warrendale, PA: Society of Automotive Engineers, 1988). Soderstrom, Carl A., M.D., Carroll, Andrew W., M.D., and Hawkins, Clarence E., The Medical Assessment of a New Soft Body Armor, Tech. Rep. ARCSL-TR-77057 (Aberdeen Proving Ground, MD: U.S. Army Armament Research and Development Command, Chemical Systems Laboratory, January 1978); NTIS accession number AD-A053 789. Stoll, Alice M. and Chianta, Maria A., Heat Transfer through Fabrics as Related to Thermal Injury, Transactions of the New York Academy of Sciences, vol. 33, no. 7, 1971, pp. 649-670.. Stone, Richard (President, Point Blank Body Armor, Inc.), personal communication, Apr. 24, 1991. Sturdivan, L., Modeling in Blunt Trauma Research presented at the Second MedicalTechnical Symposium on Soft Body Armor, Miami Beach, FL, 29 Sept. 1976, at the 83rd Annual Conference of the IACP. Sturdivan, L., personal communication, 4 Apr. 1991. Sturdivan, L., personal communication, 11 Sept. 1991. Thomas, G. E., Fatal .45-70 Rifle Wounding of a Policeman Wearing a Bulletproof Vest, Journal of Forensic Sciences, vol. 27, no. 2, April 1982, pp. 44549 Tobin, L. (cd.), The Ballistic Testing of Personal Armour, Technical Report SCRDE/91/5 (Colchester, Essex, England: Ministry of Defence, Stores and Clothing Research and Development Establishment, May 1991). U.S. Army, Ordnance Department, Office of the Chief of Ordnance, Helmets and Body Armor, 1 June 1945. U.S. Congress, Library of Congress, Technical Information Division, Personnel Anti-Fragmenta-

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46 l Police Body Armor Standards and Testing: Volume I 137. 138. 139. 140. 141. 142. 143. 144. 145. 146. 147. tion Equipment, A Bibliography by Gordon B. Ward (Washington, DC: Library of Congress, July 1955). [U.S. Department of Commerce, National Institute of Standards and Technology, Office of LawEnforcement Standards,] Summary Results and Review of Body Armor Testing To Determine Compliance with NIJ-Standard-O1O1 .03, unpublished, undated (apparently 1988-1991). U.S. Department of Defense, Military Standard Ballistic Test for Armor, MIL-STD-662D, 19 March 1984. U.S. Department of Defense, Projectile, Calibers .22, .30, .50, and 20 mm, Fragment-Simulating, Military Specification MIL-P46593, Oct. 12,1962. U.S. Department of Justice, Federal Bureau of Investigation, Uniform Crime Reports: Law Enforcement Officers Killed and Assaulted, 19811990. U.S. Department of Justice, Law Enforcement Assistance Administration, National Institute of Law Enforcement and Criminal Justice, Ballistic Resistance of Police Body Armor, NILECJ Standard 0101.00 (Washington, DC: National Institute of Justice, March 1972). [N.b.: dated March 1972 on the cover but April 1, 1972 on p. 1, the first page after the Foreword.] U.S. Department of Justice, Law Enforcement Assistance Administration, National Institute of Law Enforcement and Criminal Justice, The Ballistic Resistance of Police Body Armor, NILECJ Standard 0101.01 (Washington, DC: National Institute of Justice, December 1978). U.S. Department of Justice, National Institute of Justice, Technology Assessment Program, Ballistic Resistance of Police Body Armor, NIJ Standard 0101.02 (Washington, DC: National Institute of Justice, March 1985). U.S. Department of Justice, National Institute of Justice, Technology Assessment Program, Ballistic Resistance of Police Body Armor, NIJ Standard 0101.03 (Washington, DC: National Institute of Justice, April 1987). U.S. Department of Justice, National Institute of Justice, Technology Assessment Program, Selection and Application Guide to Police Body Armor, NIJ Guide 100-87 (Washington, DC: National Institute of Justice, February 1989). U.S. Department of Justice, National Institute of Justice, Technology Assessment Program Information Center, Compliance Testing Procedure for Police Body Armor, (undated). U.S. Department of Justice, National Institute of Justice, Technology Assessment Program Information Center, memorandum: DATE: March 18, 1988; TO: PPAA Membership; FROM: Marc H. Caplan; 148. 149. 150. 151. 152. 153. 154. 155. 156. 157. 158. 159. SUBJECT: Clarification to Police Body Armor Testing Procedures. U.S. Department of Justice, National Institute of Justice, Summary Results and Review of Body Armor Testing to Determine Compliance with NIJ-Standard-O1O1 .03, unpublished, (undated; apparently March 1988 or later). U.S. Department of Justice, Office of Justice Programs, National Institute of Justice, Technology Assessment Program, A Comparison of the Use of Three Different Mounting Fixtures for Ballistic Tests of Body Armor, NIJ Report 100-91, Coordination Draft, undated. U.S. Department of Justice, National Institute of Justice, The National Institute of Justice Body Armor Compliance Program: A Briefing Book for the Director (Draft, 5/28/91 ), unpublished. U.S. Department of Justice, National Institute of Justice, Office of the Director, The NIJBodyArmor Program, enclosed with letter of Charles B. DeWitt (Director, NIJ) to Michael B. Callaham (Senior Analyst, OTA), July 30, 1991. Viano, David C., Live Fire Testing: Assessing Blunt Impact and Acceleration Injury Vulnerabilities, research publication GMR-6690 (Warren, MI: General Motors Research Laboratories, May 24, 1989). Viano, D. C., Live Fire Testing: Assessing Blunt Impact and Acceleration Injury, Military Medicine, vol. 156, November 1991, pp. 589ff. Viano, David C., Andrzejak, Dennis V., and King, Albert I., A Review of Fatal Chest Injury by Baseball Impact in Children, mss. submitted to American Society of Mechanical Engineers, 1991. Viano, David C., Andrzejak, Dennis V., and Polley, Theo Z., Mechanism of Fatal Chest Injury by Baseball Impact in Children: Development of an Experimental Model, mss., to be published (in Clin. J. Sports Med.?) 1992. Viano, David C. and Lau, Ian V., A Viscous Tolerance Criterion for Soft Tissue Injury Assessment, Journal of Biomechanics, vol. 21, no. 5, 1988, pp. 387-399. Viano, David C., Lau, Ian V., Asbury, Corin, King, Albert I., and Begeman, Paul, Biomechanics of the Human Chest, Abdomen, and Pelvis in Lateral Impact, Accident Analysis and Prevention, vol. 21, no. 6, 1989, pp. 553-574. Viano, David C., et al., Injury Biomechanics Research: An Essential Element in the Prevention of Trauma, Journal of Biomechanics, vol. 22, no. 5, 1989, pp. 403-417. Viano, David C., et al., Biomechanics of Fatal Baseball Impact of the Chest in Children, pp. 95-103 in T.B. Khalil, H.F. Mahmood, and A.I. King (eds.) Crashworthiness and Occupant Protection in Transportation Systems, Book no. H00714,

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Police Body Armor Standards and Testing: Volume I l 47 AMD-Vol. 126 (New York, NY: American Society for Mechanical Engineering, 1991). 160. Volff, M.M., Characterization of the Wounding Back Effect, pp. 177-190 in L. Tobin (cd.), op. cit. supra. 161. Vollrath, Fritz, Spider Webs and Silks, Scientific American vol. 266, no. 3, March 1992, pp. 70-76. 162. Vollrath, Fritz, and Edmonds, Donald T., Modulation of the Mechanical Properties of Spider Silk by Coating with Water, Nature vol. 340, no. 6231, July 27, 1989, pp. 305-307. 163. Vollrath, Fritz, and Tillinghast, E., Glycoprotein Glue inside the Spider Webs Aqueous Coat, Naturwissenscha ften vol. 78, December 1991, pp. 557-559. 164. Walker, Strother H., and Duncan, David B., Estimation of the Probability of an Event as a Function of Several Independent Variables, Biometrika vol. 54, nos. 1 and 22, 1967, pp. 167-179. 165. Wantz, Robert V., What Was the Basis for the New PPAA-STD-1989-05? The Best, Most Current Knowledge Available, Reston, VA, June 5 & 6, 1990, reprinted as section 11 of The DuPont Mid-West Body Armor Symposium, sponsored by Missouri Police Chiefs, Inc., and International Association of Chiefs of Police, Chesterfield, MO, 29-31 Aug. 1990 (Wilmington, DE: The DuPont co., 1990). 166. Yen, R.T., Fung, YC., Ho, H.H., and Butterman, G., Speed of Stress Wave Propagation in the Lung, mss., undated, unpublished, Department of AMES/Bioengineering, University of California, San Diego, La Jolla, CA. 167. Yen, R.T., Ho, H.H., Tao, Z.L., and Fung, Y. C., Edema of Lung due to Impact Injury, mss., undated, unpublished, Department of AMES/ Bioengineering, University of California, San Diego, La Jolla, CA. 168. Yen, R.T., and Fung, Y.C., Thoracic Trauma Study: Rib Markings on the Lung due to Impact are Marks of Collapsed Alveoli, not Hemorrhage, mss., undated, unpublished, Department of AMES/ Bioengineering, University of California, San Diego, La Jolla, CA. U.S. GOVERNMENT PRINTING OFFICE : 1992 0 327 : QL 3 ISBN 0-16 -037987-3 79871


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