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Body Armor Safety Initiative

Date Published
January 1, 2006
Dan Tompkins

On December 23, 1975, Seattle Police Department Patrolman Raymond T. Johnson stood in the checkout line at a local market when a robbery suspect entered the store and brandished a weapon. Johnson lunged for the suspect’s gun. In the violent struggle that ensued, the suspect emptied his .38 caliber pistol, striking Johnson in the left hand and twice in the chest before fleeing.[1] Johnson survived with severe hand injuries, chest bruises, and a unique distinction—the first law enforcement officer saved in a field test of a new generation of soft body armor being conducted by the National Institute of Justice (NIJ).

Johnson was wearing body armor made with Kevlar®, an extraordinarily strong fabric developed by DuPont. NIJ, in partnership with the U.S. Army, began a program in the early 1970s to develop lightweight body armor woven from Kevlar®. Field testing began in the summer of 1975, with 5,000 armors provided to 15 urban police departments. Less than 6 months later, Johnson was the first officer saved by one of the field test armors. In all, 17 other armor-wearing officers were saved during the 1-year field test.

About the same time, NIJ developed a performance standard for body armor in collaboration with the National Institute of Standards and Technology (NIST, then known as the National Bureau of Standards),[2] followed by a voluntary testing program. The standards and testing program, which still exists today, enables body armor manufacturers to certify the performance and safety of new body armor.[3] The NIJ standard establishes minimum performance requirements for armor, and the testing program evaluates armor against the standard.

Twenty-eight years later, on the night of June 23, 2003, Forest Hills, Pennsylvania, Police Officer Edward Limbacher, wearing body armor constructed primarily of a fiber called Zylon®, threw open the side door of an unmarked Econoline van and stepped out to move in on a drug suspect. The suspect fired, striking Limbacher in the arm and abdomen with .40 caliber rounds. The shot to the abdomen penetrated the body armor Limbacher was wearing. He survived but sustained severe injuries.[4]

The Forest Hills shooting was the first case ever reported to NIJ in which body armor compliant with the NIJ standard failed to prevent penetration from a bullet it was designed to defeat.

In the 28 years between those two incidents and in the time since, at least 3,000 officers survived shootings or other incidents because they were wearing body armor meeting NIJ performance standards.[5] But the Forest Hills incident caused great concern within the law enforcement community and within the U.S. Department of Justice: Are we keeping our officers safe?

The Body Armor Safety Initiative

In November 2003, in the aftermath of the Forest Hills incident, then Attorney General John Ashcroft announced a Body Armor Safety Initiative to address the reliability of body armor used by law enforcement and to review the process by which body armor is certified.[6]

As part of the initiative, NIJ tested both new and used ballistic-resistant vests made with Zylon®.[7] NIJ also tested upgrade kits distributed by the manufacturer of the armor in the Forest Hills incident to retrofit some models of its Zylon®-based vests. And NIJ began a review of its standards and testing program for ballistic-resistant vests, which has resulted in interim changes to the standards and testing process. Read on for the results of these tests and a summary of changes to the standards and testing program.

Why Did the Vest Fail?

Even before the announcement of the Attorney General’s initiative, NIJ staff contacted representatives of the Forest Hills Police Department and the Allegheny County Police Department (the agency handling the criminal investigation of the shooting) to examine the vest, the weapon, and the ammunition used in the shooting to determine why the vest failed. The examination found that:

  • The bullet velocity from the gun used in the shooting was not greater than the bullet velocity NIJ uses in compliance testing for the type of vest Limbacher was wearing.
  • The physical properties of the bullets used in the shooting were similar to bullets used in NIJ’s compliance testing of the type of vest Limbacher was wearing, although there were some differences in bullet geometry and in how the bullet deformed on impact.
  • The tensile strength of Zylon® yarns removed from the back panel of Limbacher’s vest was up to 30 percent lower than Zylon® yarns from new armor that the manufacturer provided for this study. (The front panel, which was penetrated in the incident, was being held as evidence in the criminal case against the shooter, so it was not available for testing.)

NIJ also developed a detailed test plan simulating the Forest Hills incident to isolate the factors deemed most likely responsible for the vest failure. Test designers identified five potential causal factors: ballistic material tensile strength, bullet type, the gun barrel twist, the shot angle, and the location of the shot on the armor.

NIJ obtained and tested 32 ballistic panels of the type worn in the Forest Hills incident. Half of the panels were tested new, and the other half were artificially aged for 5 months in a chamber exposing the panels to controlled temperature and humidity conditions until the tensile strength of fibers in the vests matched those of fibers from the rear panel of the Forest Hills vest.

Each of the 32 panels was shot six times. None of the 192 shots penetrated the panels. NIJ is continuing efforts to determine the cause of the Forest Hills failure but is still unable to draw a definitive conclusion.

Testing the Upgrade Kits

As part of the Attorney General’s initiative, NIJ was directed to test any upgrade kits offered by body armor manufacturers to retrofit existing vests. The tests would determine if the upgrade kits met the NIJ performance standard when used with the original vest they were designed to supplement. One manufacturer, Second Chance Body Armor, Inc. (the manufacturer of the body armor worn in the Forest Hills incident), offered an upgrade kit to users of some models of Zylon®-based body armor—an additional ballistic panel to be inserted into the armor. At NIJ’s request, Second Chance provided 50 sets of armors and matching upgrade kits for three soft armor protection levels—Level IIA, Level II, and Level IIIA.[8] The samples included both new and used upgrade kits, and the majority of the armors had been previously worn.

NIJ’s testing found that the Second Chance upgrade kits added protection when used with the existing used body armor. However, the level of protection did not meet existing NIJ performance standards for new body armor.

Also, the vest/upgrade kit combinations in all three protection levels experienced excessive “backface signatures.” This means that the bullets didn’t penetrate the vest, but the impact of one or more bullets created a “dent” of more than 44 mm (almost 2 inches) into the clay in back of the vests during testing, a depth that may cause serious injury. Six of eight Level IIA armors, two of eight Level II armors, and five of eight Level IIIA armors ultimately tested experienced excessive backface signatures during testing.

Further, two of the eight Level IIIA vest/upgrade kits (designed to offer protection against high velocity 9 mm and 44 magnum bullets) experienced penetrations.

Despite the safety questions raised by these test results, it is important to note that the upgrade kits did add some measure of protection. Officers who have received these upgrade kits should wear them.

Testing Used Armor

Heat, moisture, ultraviolet and visible light, detergents, friction, and stretching may all contribute to the degradation of fibers used in the manufacture of body armor. Body armor manufacturers design their armor and provide care instructions to minimize the effects of these degrading properties.

Because the evidence showed an unexpected degradation rate in Zylon®-based armor, NIJ conducted ballistic and mechanical properties testing on 103 additional used body armors containing Zylon®. Law enforcement agencies across the United States provided these vests to NIJ. Sixty of these used armors (58 percent) were penetrated by at least one round during a six-shot test series. Of the armors that were not penetrated, 91 percent had backface deformations in excess of that allowed by the NIJ standard for new armor. Only four of the used Zylon®-containing armors met all performance criteria expected under the NIJ standard for new body armor compliance. Although these results do not conclusively prove that all Zylon®-containing body armor models have performance problems, the results show that used Zylon®-containing body armor may not provide the intended level of ballistic resistance.

In addition, armors were visually inspected and given one of four condition ratings from “no visible signs of wear” to “extreme wear and abuse.” Testers found no correlation between the level of visible wear of the body armor panels and the ballistic performance of those panels. This finding is important because even used Zylon® body armor that appears to be in good condition may not provide an acceptable level of performance.

Exploring Fiber Degradation

With funding provided by NIJ, polymer scientists at NIST are probing down to the molecular level to learn more about how Zylon® degrades. They are examining the chemical changes that occur as the fibers degrade, the trace contaminants on fibers that may contribute to degradation, the moisture content of fibers, and mechanical strength differences among individual fibers and what causes those differences.

Initial findings have isolated the ballistic performance degradation to the breakage of a small part of the Zylon® fiber molecule. Breakage of this part of the molecule, called the oxazole ring, occurs as a result of exposure to both moisture and light. When there was no potential for external moisture to contact Zylon® yarns, there was no significant change in the tensile strength of these yarns. Therefore, it appears that external moisture is necessary to facilitate the degradation of Zylon® fibers.

In addition to this work, NIJ is also funding research on other personal protective equipment to better understand how and why ballistic-resistant materials degrade over time.[9]

Improving the NIJ Standard and Compliance Testing Program

NIJ has undertaken a complete review of its performance standard for ballistic-resistant armor and the compliance testing program. It solicited input from law enforcement and corrections agencies, fiber and armor manufacturers, and standards and testing organizations.

NIJ’s 2005 Interim Requirements for Bullet-Resistant Body Armor, issued in August 2005, take into account the possibility of ballistic performance degradation over time. These interim requirements will help ensure that officers are protected by body armor that maintains its ballistic performance during its entire warranty period.

Under the 2005 interim requirements, NIJ will not deem armor models containing PBO (the chemical basis of Zylon®) to be compliant unless their manufacturers provide satisfactory evidence to NIJ that the models will maintain their ballistic performance over their declared warranty period.

NIJ recommends that agencies that purchase new ballistic-resistant body armor select body armor models that comply with the NIJ 2005 Interim Requirements. View lists of models that comply with the requirements:

NIJ is also encouraging manufacturers to adopt a quality management system to ensure the consistent construction and performance of NIJ-compliant armor over its warranty period. In the future, NIJ will issue advisories regarding body armor materials that appear to create a risk of death or serious injury as a result of degraded ballistic performance. Any body armor model that contains any material listed in such an advisory will be deemed no longer compliant with the NIJ standard unless the manufacturer satisfies NIJ that the model will maintain ballistic performance over the declared warranty period.

Life Vests

There are at least 3,000 other stories like that of Seattle Police Officer Raymond T. Johnson. That’s 3,000 families spared the anguish of death or debilitating injury to a loved one in the line of duty. And cases like that of Forest Hills Officer Limbacher’s are rare—a testament to the reliability of soft body armor. Even so, that single failure prompted NIJ to review its body armor program and to conduct an intensive examination of why that failure occurred. Through this review and research, NIJ remains committed to working for the safety of law enforcement officers.

The evidence is clear: An officer not wearing armor is 14 times more likely to suffer a fatal injury than an officer who is. Therefore, the most important message for the law enforcement community is that officers should continue to wear their body armor.

At least 3,000 officers would second that advice.

NCJ 214112

For More Information

About the Author
Dan Tompkins is a writer/editor at the National Institute of Justice and Editor of the NIJ Journal.

Date Published: January 1, 2006