BLACK MOTORISTS have long complained that American police officers tend to target them for traffic stops. A study by the Justice Department, published in 2013, found that black drivers were 31% more likely to be pulled over than white ones; other interactions with law enforcement are characterised by similar racial imbalances.
Such figures do not by themselves prove that bias is to blame. It is hard to distinguish how much of this imbalance can be attributed to race-specific differences in driving behaviours—such as adherence to traffic laws or the amount of time spent on roads in areas where police are present—and how much is driven by racial profiling. But new research suggests that discrimination is at least part of the problem.