Black and Hispanic police officers tend to stop, arrest and use force against civilians less often than white officers do, and female officers of all races use less force than their male colleagues, a new case study of the Chicago Police Department suggests.
Information on the demographics and behavior of thousands of Chicago police officers revealed how officers of different races and genders acted while on similar patrol assignments. While the results do not shed light on why these differences exist, they do suggest that diversifying U.S. police departments — which have historically been nearly all white and male — may improve police treatment of minority communities, researchers report in the Feb. 12 Science.
“When I got the paper, I literally at one point said, ‘hot damn,’” says Phillip Goff, a behavioral scientist at Yale University who wrote a commentary on the study published in the same issue of Science. “I was a skeptic about demographic reform previously, and now I am a convert.… Demographics reform in policing actually has the potential to dramatically change behavior.”
Diversifying law enforcement is one of the oldest, most frequently proposed police reforms, Bocar Ba, an economist at the University of California, Irvine, said in a Feb. 8 news conference at the annual meeting of the American Association for the Advancement of Science, held online. Calls for changes to law enforcement have been particularly strong within the last year, in response to the police killings of George Floyd, Breonna Taylor and other unarmed Black civilians (SN: 7/9/20). But so far, scientific research has not provided clear answers about how police officer demographics may influence their law enforcement activities.
The problem has been a lack of available data, Ba said. Researchers need detailed enough information on officers’ patrol assignments to compare officers of different races and genders working under similar circumstances. “Until now, it has been extremely difficult to make this sort of apples-to-apples comparison, because police agencies have not released the necessary data,” Ba said.
Over three years, Ba and colleagues peppered various city and state agencies with open-records requests and appeals to collect data on officers in the Chicago Police Department. Those data included officers’ race, gender and daily patrol assignments, as well as timestamped and location-tagged records of when those officers stopped, arrested or used force on civilians. In total, the researchers examined 2.9 million officer shifts and 1.6 million enforcement activities performed by nearly 7,000 officers from 2012 to 2015. The team looked at how officers of different backgrounds behaved while patrolling the same neighborhood at the same time of day, day of the week, month and year.
This study is “one of the most comprehensive and sophisticated” examinations of how officer demographics affect policing to date, says Robin Engel, a criminal justice researcher at the University of Cincinnati who was not involved in the work. “We now have rigorous, robust evidence that suggests there are differences in behavior across racial and gender groups within our police departments, and that’s important for a whole host of things. It’s important for recruitment, and it’s also important for our training of officers.”
Black officers made 15.16 fewer stops, 1.93 fewer arrests and used force 0.1 fewer times than their white counterparts, on average, over the course of 100 shifts. That corresponded to a 29 percent reduction in stops, 21 percent reduction in arrests and 32 percent reduction in use of force among Black officers, compared with the average enforcement rates among their white peers.
Those differences arose primarily because Black officers were less likely to stop and use force against Black civilians. Black officers also relied less on discretionary enforcement activities, like stopping people for “suspicious behavior,” and focused less on petty crimes, such as drug offenses. Black and white police officers’ arrest rates for violent crime were more comparable.
Like their Black colleagues, Hispanic officers conducted fewer stops, made fewer arrests and used force less often than white officers, although the difference was not as stark. Hispanic officers made 2.84 fewer stops, 0.44 fewer arrests and 0.04 fewer uses of force per 100 shifts, on average. That represented a 6 percent, 5 percent and 12 percent reduction, respectively, compared with white officers’ average stop, arrest and use-of-force rates.
Female officers of all races made 7 percent fewer arrests than their average male peers and used force 28 percent less often. Like Black officers, Hispanic and female officers made fewer arrests and used force less than white and male officers primarily because they were less likely to arrest and use force against Black civilians.
Engel cautions that this study alone cannot explain why officers of different races and genders police differently. It may be due to officers’ personal biases or differing responses to police training, she says, or perhaps civilians respond differently to officers of different races or genders. Future research will have to take a deeper dive into officer-civilian interactions to tease out the reasons for these demographic differences, and investigations of police behavior in other cities will be necessary to determine whether these results hold up outside Chicago.
The trends uncovered in this case study do provide compelling evidence that diversifying police departments “is an important part of any comprehensive effort at police reform,” says David Sklansky, a law professor at Stanford University not involved in the work. The data suggest that hiring more nonwhite and female officers may reduce violence, particularly against minority civilians.
“It’s not just that Black and Hispanic officers conduct fewer stops — it’s that they conduct fewer stops of Black suspects in situations not involving serious crime,” Sklansky says. “That’s clearly an improvement … partly because [reducing those stops] reduces the number of situations that can lead to violence.”