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Traffic Stops Suffer From Racial Disparities Even When Controlling for Conditions, New Research Finds

A report by the Public Policy Institute of California found that Black drivers in California are more likely to be stopped and searched than white drivers, showing the need for more reforms to address racial injustice,

A police car drives by an intersection in the rain where the word stop is painted on the ground.
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Police in California are more likely to search Black people during traffic stops than white people, with ramifications throughout the rest of the criminal justice system, according to researchers behind a new analysis of nearly 4 million traffic stops in the state.

The study, Racial Disparities in Law Enforcement Stops, was released last month by the Public Policy Institute of California with support from Arnold Ventures. This work continues efforts to study and address racial disparities in California’s criminal justice system. While Black residents make up just 6% of the state’s population, they account for 16% of the state’s arrests. They also account for roughly a quarter of California’s prison and jail populations. 

Proportion of California residents who are Black
Proportion of residents arrested in California who are Black

Though the passage of reforms such as Proposition 47 have narrowed the state’s racial disparities in arrests thanks to the reclassification of drug and property offenses, the data on traffic stops shows racial injustice continues to perpetuate within the legal system. Meanwhile, even as traffic stops serve as one of the most frequent interactions between police and residents, there is a growing body of evidence that this enforcement does little to promote community safety.

We know that, basically since cars have been on the road, police have been doing traffic enforcement, and I think now is a moment to step back and think about what they are enforcing, and why,” said Anita Ravishankar, director of criminal justice research at Arnold Ventures. I think what we get from actually digging into these numbers is a real moment to pause — to say, it doesn’t have to be like this, this is not making us safer. And we’re actually spending a lot of public resources doing it.”

Community Concerns Reflected in Data

In 2015, state lawmakers passed bills requiring police departments to collect data on certain use of force incidents along with data on police stops, including information such as race, gender, and sexual orientation. It’s this data, collected from the 15 largest law enforcement agencies in California, which formed the basis of PPIC’s study. 

Researchers found that, in California, Black motorists are more than twice as likely to be searched by the police than their white counterparts. While stops led to a search of Black people in 20.5% of cases, that figure was 8.2% for white people. Notably, police are less likely to find contraband such as drugs and guns in their searches of Black people. Still, Black people are more likely to be arrested after a traffic stop. That figure is one in 10, compared to just over one in 20 white people. 


Black motorists in California are more than twice as likely to be searched by the police than their white counterparts.

Local law enforcement agencies such as sheriff’s departments and city police have the largest racial disparities in the outcomes of their stops, compared to the California Highway Patrol, who rarely search people after a stop. For local law enforcement, more than one-third of traffic stops are for non-moving violations such as expired registration or illegal window tints.

Police are also more likely to escalate traffic stops of Black motorists. In 28% of those stops, the officer asks the person to either step out of their car, handcuffs them, or involves a weapon, according to the report. White motorists experience that just 13% of the time. And officers are three times more likely to involve their weapon, such as aiming though not necessarily firing a gun or taser, when stopping a Black person in contrast to a white one.

Even when researchers accounted for contextual factors — things like location and reason for the stop such as knowledge of an outstanding warrant — they still found evidence of racial disparities.

All of those contexts do matter. We see that once we make adjustments for them the disparities decrease but more importantly they’re still there,” said Magnus Lofstrom, policy director of criminal justice at PPIC who worked on the report.

He said that the research will be key to advancing reforms since lawmakers now have crucial data to back up anecdotal evidence. The data most definitely supports concerns voiced by communities of color about inequities and different experiences within law enforcement.”

Lofstrom recommended that local law enforcement agencies re-examine traffic stops for non-moving violations and reconsider whether searches were needed in the first place given that so few resulted in contraband.

The data supports findings from the Stanford University Open Policing Project that nationally, Black drivers are more likely to be stopped and searched than white drivers.

Impacted communities have been telling us these things for a long time,” said Ravishankar Systematic data collection gives us greater insight into the widespread nature of the problem and allows us to design and implement more effective policy solutions.”

Local Leaders Call for Change

In California, there’s already movement within the state’s law enforcement to curb racial inequities resulting from policing.

Sacramento Police Chief Daniel Hahn, who consulted on the report, said he wasn’t surprised by its findings and implored officials to dig deeper, particularly into identifying why a stop is conducted in the first place. You know, our stops are disparate in our […] department. But what’s even more disparate than our stops is the suspect descriptions that are called into our police department are overwhelmingly African-American suspects,” he said.

For his part, Hahn said he requires his officers to take history classes that cover the evolution of the city’s neighborhoods. Too many times we don’t know the truth,” he said.

In 2019, the City of Berkeley formed a working group to address police problems such as use of force and disparities in traffic stops. Officials there passed a package of reforms in early 2021 that included a plan for the police to no longer make traffic stops for minor offenses such as expired license plates or broken lights. Also under the reforms, police would be required to obtain written consent for searches and could not ask about probation or parole status in most cases.

We cannot change what is past, but we can build accountability, root out racial injustice and fight systemic racism,” California Gov. Gavin Newsom said this year when signing bills to increase police accountability. (Kevork Djansezian/​Getty Images)

At the state level, Gov. Gavin Newsom signed into law in September a set of bills aimed at increasing police accountability and curbing excessive use of force. Black residents are approximately three times more likely to be seriously shot, injured, or killed by the police relative to their part of the state’s population.

Too many lives have been lost due to racial profiling and excessive use of force. We cannot change what is past, but we can build accountability, root out racial injustice and fight systemic racism,” the governor said in the signing ceremony.