Colorado and Washington saw vehicle searches by police officers fall dramatically after legalizing marijuana -- a trend that could have implications in California, where voters legalized recreational pot last November.
Researchers with Stanford University's Open Policing Project found the trend buried in data on 130 million traffic stops by state patrol officers, including millions by the California Highway Patrol. They reviewed data from 31 states, but the steep fall in searches in Colorado and Washington surprised the researchers.
"It really did plummet," said Stanford's Sharad Goel of the search rates. "When you take away a common reason for conducting a search, then there are fewer searches." The impacts were felt by all drivers, Goel said, not just those with marijuana in their cars.
In Colorado and Washington, the number of drivers found with contraband fell by 40 percent in the year following legalization. Nothing like that happened in other states, according to the report.
Searches that resulted in drug-related misdemeanors also cratered after the two states legalized pot.
Racial Disparities Remain
But the numbers reveal stark racial disparities in searches by state patrol officers, including in California. Across the states the report reviewed, black and Hispanic drivers were about twice as likely to be searched as white drivers. Racial disparities in search rates -- how often law enforcement searched drivers after stopping them -- were found across over the country, from Massachusetts to Arizona.
And while marijuana legalization slashed the number of searches in Colorado and Washington, it didn't transform the disparities, the researchers say. "There's still evidence of this racial disparity," Goel said.
The findings could have implications for California.
"If officers are conducting searches on suspicion of marijuana, and now you've legalized marijuana, those searches are almost certainly going to drop," Goel said.
But if the Golden State follows trends in Colorado and Washington, existing racial disparities in police searches may not change.
California voters approved marijuana legalization last year by a wide margin. Recreational pot will go on sale starting January 1, 2018.