Study: Police stop black and Latino drivers more often than whites

Police officers across the United States are more likely to cite, search and arrest black and Latino drivers during routine traffic stops than white drivers, according to an analysis of traffic stop data conducted by Stanford University researchers.

The findings are based on a nationwide database of state patrol stops created by Stanford researchers, which they say may be the largest compilation of traffic stop data ever assembled. The database, released to the public Monday as part of the Stanford Open Policing Project, contains details from more than 100 million records of traffic stop-and-search data across 31 states between 2011- 2015 as part of an effort to statistically analyze police practices.

While several factors - such as time spent on the road or driving behavior, among others - can contribute to traffic stop disparities and don't necessarily indicate racial bias, researchers said they conducted supplemental tests in which they found indication that minorities are held to a double standard and searched on the basis of less evidence.

“Not only did we find minorities are ticketed and arrested more often, we also found that police in general will use a lower bar to search minorities than whites. They have a lower threshold,” said Cheryl Phillips, a journalism lecturer at Stanford and part of the university's Computational Journalism Lab.

If, for example, an officer has a 20 percent suspicion that a white driver has contraband, drugs or weapons in the person's vehicle, they would conduct a search. But for a minority driver, that threshold of suspicion could be as low as five percent, she said.

“In general, we found evidence of discrimination and disparities to be across all states and across all geographies where we have the data,” said Phillips, adding that they found patterns of disparity even after taking into account gender, age and time of day in which the driver was stopped.

In the Bay Area, black drivers were pulled over at about twice the rate that white drivers were, the data shows. In San Mateo County, police pulled over 23 black drivers for every 100 black drivers they encountered on the road, compared to just 12 white drivers for every 100 encountered. In San Francisco County, police pulled over 20 black drivers for every 100 they countered, compared to eight out of 100 white drivers. Santa Clara County officers pulled over 13 black drivers for every 100 compared to 7 percent of whites and in Contra Costa, 14 blacks for every 100 encountered were pulled over compared to 6 whites per 100.

About 20 states either declined requests for the data or said they do not collect it, according to researchers.

Retired Superior Court Judge and former San Jose police auditor LaDoris Cordell said she wasn't surprised by the findings.

“It's what communities of color have been saying for years,” Cordell said. “You see a black person or a Latino and they're immediately suspicious. Just because of the color of our skin.”

The Stanford Open Policing Project - a unique partnership between the Stanford Computational Journalism Lab and the Stanford School of Engineering - is aimed at combining statistical analysis with data journalism in order to help researchers, journalists, and policymakers investigate and improve police interactions with the public.

The group began gathering data in 2015 and is now in the process of compiling traffic data at the city level.

“We are at a place in this country where the public and especially communities of color are demanding more accountability in policing,” Cordell said.

The California Peace Officers Association was not available for comment Friday and the National Association of Police Organizations did not respond to requests for comment.