A history of nearly exclusively white male police forces in the U.S. has made diversifying personnel one of the oldest and most often proposed police reforms, but data challenges have precluded micro-level evaluations of its impact.
Using newly collected personnel data and millions of ultra-fine-grained records on officer deployment and behavior, we conduct a detailed quantitative case study of diversity in the Chicago Police Department.
We show how officers from marginalized groups are consistently assigned to different working conditions than white and male officers, meaning they typically encounter vastly different circumstances and civilian behaviors.
As a result, coarse agency- or district-level analyses often fall short of all-else-equal comparisons between officer groups, making it difficult to disentangle officers’ behavior from the environments in which they work—a crucial first step in evaluating the promise of diversity reforms.
To assess behavioral differences between officers of varying racial, ethnic and gender profiles, we leverage detailed records of daily patrol assignments to evaluate officers against their counterparts working in the same collections of city blocks, in the same month and day of week, and at the same time of day.
Compared with white officers facing identical conditions, we show Black and Hispanic officers both make substantially fewer stops, arrests, and use force less often, especially against Black civilians. Much of the gaps in stops and arrests are due to a decreased focus on discretionary contact, such as stops for vaguely defined “suspicious behavior.”
Hispanic and white officers exhibit highly similar behavior toward Hispanic civilians, though Hispanic officers who speak Spanish appear to make fewer arrests in general than those who do not speak Spanish.
Within all racial/ethnic groups, female officers are substantially less likely to use force relative to male officers.
Taken together, these results show the substantial impact of diversity on police treatment of minority communities, and emphasize the need to consider multiple facets of police officers when crafting personnel-driven reforms.