Racial disparities in traffic stops increase when officers can see a driver’s race.

Evidence

In the largest analysis to date—consisting of nearly 100 million traffic stops conducted by dozens of agencies between 2011 to 2017—an interdisciplinary team of researchers led by Sharad Goel as part of the Stanford Open Policing Project found that Black drivers were stopped more often than White drivers (Pierson et al., 2019). Trying to isolate the influence of race from other factors such as crime, the researchers used daylight saving time as a type of naturalistic experiment (Grogger & Ridgeway, 2006). They found that Black drivers were less likely to be stopped after dusk, when it is dark and presumably harder to ascertain a driver’s race, than at the same time of day during parts of the year when it is still light out and easier to ascertain a driver’s race. In our analysis of pedestrian and traffic stops in Oakland, we also found that the magnitude of racial disparities in stops was greater when officers indicated they could determine the community member’s race prior to making the stop. — Joseph Avery, Jim Sidanius, Joel Cooper, Gregory Davis, Amanda N., Bias in the Law, 363

Categorization

• SEED: Daylight saving time as a naturalistic experiment on racial visibility is a striking, counterintuitive research method — an article on how daylight hours function as a kind of ‘visibility lever’ for police bias could be compelling.
• SHARE: For someone interested in quasi-experimental research design — the daylight-savings-time trick for isolating visibility-based bias is exactly their niche.
• XREF: connects to: Ambiguous police stops confirm minorities’ belief that officers are racist