The test results revealed that most Zylon-containing vests showed deformations in excess of 0101.04 Standard's 44 mm backface signature limit. Such increased deformation can lead to serious injuries, including backface signature injuries which have occurred in the field. Although the vest is successful in containing the round, it is not effectively dissipating energy enough to prevent large amounts of vest deformation at the area of impact. Therefore, open penetrating wounds occurred even though the bullet did not penetrate the vest. Although the underlying cause of backface signature injuries is unknown, energy density is likely to play a role in the mechanism. Energy density is defined as the energy per unit area and has been previously used in less lethal skin penetration research. Two injury patterns typically occur with less lethal projectile impacts. Impact from larger caliber rounds often result in blunt trauma injuries such as rib fractures. However, skin penetration is the primary concern from a smaller caliber round such as 12 gauge projectile. In addition to skin penetration, localized rib fractures may also occur. Until further advancements are made, officers must continue to wear the vests that have been provided. Review of the FBI's Law Enforcement Officers Killed and Assaulted (LEOKA) reports indicate that 148 officers may have survived gunshot wounds to the torso had they been wearing body armor at the time of the shooting. The sample included 16 individuals from the IACP/DuPont Kevlar Survivors' Club, a voluntary organization which permits membership to those law enforcement personnel whose lives have been saved by the use of personal body armor. Table, figures, references