Less-Lethal Weapons and Civilian Injury in Police Use of Force Encounters: A Multi-agency Analysis.

Police use-of-force is a growing public health concern, with recent estimates suggesting that over 70,000 people are injured by police each year. To reduce the risk of injury to civilians, most police agencies authorize the use of various less-lethal weapons. However, to date, there is little consensus as to which types of less-lethal weapons are most effective at reducing injury risk. In this study, we test the differential effects of less-lethal weapons on civilian injury and injury severity using data on 2348 use-of-force incidents originating from 17 large urban and metropolitan law enforcement agencies from 2015 to 2019. Specifically, we assess the injury risks associated with conducted energy devices, chemical agents, impact weapons, and police canines, while controlling for a robust set of officer, civilian, and situational characteristics. Our results indicate that chemical agents reduce the risk of hospitalization or death significantly more than other weapon types, while police canines increase the risk of all injury outcomes significantly more than other weapon types. Adjusting for incident characteristics, chemical agents are predicted to cause hospitalization or death in 4% of cases, compared to 13% for conducted energy devices, 16% for impact weapons, and 37% for police canines. These findings suggest that civilian injury may be reduced through use-of-force policies that prioritize less severe modalities of force, though more research is needed on the contextual and long-term effects of these weapons.