How Dangerous Is Driving Stoned?

With marijuana now fully legal in two states and others set to follow, should authorities be cracking down on stoned driving? Experts say doing so could be tough, because standard field sobriety tests aren't very good at detecting tokers, and the outcome depends a lot on how used to being stoned the driver is, the New York Times finds. Researchers note that though driving while high isn't risk-free—THC in the bloodstream is associated with a twofold rise in accident risk—driving drunk is associated with a 20-fold rise in accident risk among young drivers, suggesting that limited resources should be used to focus on drivers under the influence of alcohol.

The difference in risk is partly owed to the fact that drunk drivers tend to overestimate their abilities, while the opposite is true for stoned motorists, experts say. "The joke with that is Cheech and Chong being arrested for doing 20 on the freeway," a UCLA professor of public policy says. Experts recommend stoned driving be dealt with by persuading people not to mix marijuana with alcohol, and by discouraging people from smoking away from home. Police officers in Washington and Colorado have been trained to spot signs of stoned drivers, though a lawyer at a Denver firm specializing in marijuana-related issues says he hasn't seen any increase in drugged-driving cases since the state legalized pot. "People realize that Colorado is really under the microscope," he tells Time. "And it’s our duty as a state to be responsible." (More marijuana stories.)