Diversification is a widely proposed policing reform, but its impact is difficult to assess. We used records of millions of daily patrol assignments, determined through fixed rules and preassigned rotations that mitigate self-selection, to compare the average behavior of officers of different demographic profiles working in comparable conditions. Relative to white officers, Black and Hispanic officers make far fewer stops and arrests, and they use force less often, especially against Black civilians. These effects are largest in majority-Black areas of Chicago and stem from reduced focus on enforcing low-level offenses, with greatest impact on Black civilians. Female officers also use less force than males, a result that holds within all racial groups. These results suggest that diversity reforms can improve police treatment of minority communities.
Using a rare geocoded census of SWAT team deployments from Maryland, we show that militarized police units are more often deployed in communities with large shares of African American residents, even after controlling for local crime rates. Using nationwide panel data on local police militarization, we demonstrate that militarized policing fails to enhance officer safety or reduce local crime. Finally, using survey experiments – one of which includes a large oversample of African American respondents – we show that seeing militarized police in news reports may diminish police reputation in the mass public.