How often does race come into play when cops stop motorists? The answer is: Nobody really knows. In the last few years, videos of traffic stops have created a national debate about the way law enforcement treats minorities. The case of Sandra Bland, an African American woman who died in jail after a Texas state trooper stopped and then arrested her in 2015, is among the recent examples of confrontational behavior by officers caught on tape.

Bland’s case and others have spurred calls for more reliable information — everything from police video to data logged every time someone is pulled over — because traffic stops are one of the most common ways members of the public interact with the police.

But this information is hard to come by because of a patchwork of laws and regulations across the country, a research project at Stanford University has found. The project — Law, Order & Algorithms — has found that even though a little more than half the states, 31, routinely collect data on race (based on officer perception), the way it’s collected is far from uniform.

Even where data exist, some states have not analyzed it. Even fewer states make the information available for public review.

In Nevada, officers record the driver’s race only if they issue a ticket or make an arrest. In South Carolina, officers note a driver’s race only when the driver is not ticketed or arrested. Georgia has a spot on its traffic warning forms for race, but not on its tickets. Even then, troopers aren’t required to fill it in. At least three states collect information but don’t compile the data or analyze it. Maine, for example, collects the information on paper only.

In the rest of country, 15 states either did not respond or did not say whether, or how, any data were collected. Four states said they did not track the race of drivers they stop at all. In one of those, Louisiana, the state police said it was “not required to maintain such information because we have a written policy against racial profiling.”

The Montana Highway Patrol has been recording the race of every driver it stops since 2003 but began paying outside researchers to examine the data for bias only since 2012. In 2013, the patrol was sued, accused of detaining Latinos for minor traffic violations as a way to check their immigration status. The state settled that lawsuit in 2015. The patrol didn’t admit to any wrongdoing but agreed to continue paying for outside analysis of highway patrol stops, to adhere to its policy against racial profiling and to put more oversight in place.

Without knowing who is stopped by whom and why, understanding how police can improve their interaction with minorities is difficult, experts said.

“We think that there are issues, but nobody is minding the chicken coop anymore,” said Jim Taylor, legal director for the American Civil Liberties Union in Montana, which has decided to obtain and analyze state patrol stops itself.

At Stanford, researchers and journalists are seeking to gather and analyze as many as 100 million traffic stops across the U.S., with support from the Knight Foundation. The goal is to assemble and put online existing traffic-stop data for journalists and academics.

In 2015, California and Rhode Island enacted new laws requiring state and local police agencies to collect and report stop-and-search information. The Obama administration also recently began the Police Data Initiative to study ways to improve community policing, particularly in diverse communities.

“I think there are many, many agencies out there that are conducting daily operations that have no idea of how those operations might be impacting different communities or different people,” said Jim Burch, vice president for strategic initiatives with the Police Foundation, a national organization working on the Obama initiative.

Read the full story at

Sam Corbett-Davies, Jan Overgoor, Emma Pierson and Camelia Simoiu, Ph.D. students at Stanford University and part of the Law, Order & Algorithms project, contributed to this report. The project is a partnership between assistant professor Sharad Goel in the Stanford Department of Management Science & Engineering and Stanford journalism lecturer Cheryl Phillips and Vignesh Ramachandran with the Stanford Computational Journalism Lab. The group is gathering and analyzing about 100 million traffic stops across the U.S. and expects to make all the data available online.