A Randomized Control Trial Evaluating the Effects of Police Body-worn Cameras
Yokum, David, Anita Ravishankar, and Alexander Coppock. 2019. Proceedings of the National Academy of Sciences 116(21): 10329–10332. doi:10.1073/pnas.1814773116
Police body-worn cameras (BWCs) have been widely promoted as a technological mechanism to improve policing and the perceived legitimacy of police and legal institutions, yet evidence of their effectiveness is limited. To estimate the effects of BWCs, we conducted a randomized controlled trial involving 2,224 Metropolitan Police Department officers in Washington, DC. Here we show that BWCs have very small and statistically insignificant effects on police use of force and civilian complaints, as well as other policing activities and judicial outcomes. These results suggest we should recalibrate our expectations of BWCs’ ability to induce large-scale behavioral changes in policing, particularly in contexts similar to Washington, DC.
Fig. 1 from paper: Average difference (with 95% confidence interval) between BWC and non-BWC groups, per 1,000 officers over a year for police use of force, complaints filed against officers, and arrests for disorderly conduct. We show findings from both our difference-in-means (DIM) estimator and ordinary least-squares (OLS) regression including pretreatment covariates.