The Power of Observation: An Empirical Analysis of the Effects of Body Worn Cameras on Police Use of Force and Productivity

Abstract

Controversial police use-of-force incidents have eroded police legitimacy, and body-worn cameras (BWCs) have received extensive attention as a key reform. I study the causal effects of BWCs on the use of force and law enforcement outcomes. Previous studies that randomized BWC deployment at the officer level within a single agency faced empirical challenges as (1) the control group officers are also indirectly affected by BWCs due to interactions with the treatment group officers (spillover), (2) there may be fundamental differences between agencies that agree to be researched and agencies that do not (site-selection bias), and (3) researchers could not directly examine agency-wide variables such as crime rates and public opinion. I overcome these limitations by conducting the first nationwide study of BWCs across more than 1,000 agencies in the US. I find that BWCs lead to substantial decreases in the use of force, both against whites and minorities. Nationwide, they reduce police-involved homicides by 58%. In contrast to previous studies on police accountability, I find no evidence of an association between police oversight through BWCs and reduction in policing efforts. By examining social media usage from Twitter, I find that BWC adoption has improved public opinion toward the police. These findings imply that BWCs can be an important tool for improving police accountability without sacrificing policing capabilities.