Examination of the failed Zylon vest revealed that the bullet velocity from the gun used was not greater than the bullet velocity the National Institute of Justice (NIJ) used in compliance testing, the physical properties of the bullets used were similar to bullets used in NIJ’s compliance testing of the type of vest worn, and the tensile strength of Zylon yarns removed from the back panel of the vest was up to 30 percent lower than Zylon yarns from new armor that the manufacturer provided for this study. In 2005, Interim Requirements for Bullet-Resistant Body Armor was issued. Interim requirements include: (1) 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; (2) agencies that purchase new ballistic-resistant body armor select body armor models that comply with the NIJ 2005 Interim Requirements; and (3) that manufacturers adopt a quality management system to ensure the consistent construction and performance of NIJ-compliant armor over its warranty period. After the 2003 shooting of a Pennsylvania police officer, in whom the body armor made of Zylon failed to prevent penetration from a bullet, the U.S. Attorney General announced a Body Armor Safety Initiative to address the reliability of body armor used by law enforcement and review the process by which body armor is certified. This article presents the results of these tests and a summary of changes to the standards and testing program.