Association for Public Policy Analysis & Management

We examine network effects in police force by officers who, through a random lottery, attended the police academy together in Chicago. On-duty injuries cause peers to substantially increase the use of force in the following week, resulting in more civilian injuries. The increased force use does not lead to a significant decrease in officer injuries. Our results suggest that policies aiming to reduce the use of force must consider the effects on officer safety. Increasing the risk to officers will increase force use both directly and through their peer group. Policies that reduce the risks to officers may also reduce the risk to suspects.