Four Western states and the District of Columbia have legalized recreational marijuana, and voters in half a dozen more states may vote next year on pot legalization. That’s leading law enforcement officials and entrepreneurs to try to come up with better ways of testing for driving while stoned, reports NPR. Police may spot impaired drivers by noting driving behavior, coordination, mannerisms and physical cues. A handheld test can quickly determine if someone is legally drunk based on ethanol in the breath, but there’s no instant test for marijuana intoxication. In Washington state, one of 18 states that have set limits on marijuana intoxication while driving, law enforcement can seek a warrant for a blood draw to test for THC, the main ingredient in marijuana. It can take weeks to get lab results.
With more Washington state drivers arrested with marijuana in their systems since the state legalized recreational marijuana, there’s a growing need for a fast way to identify impaired drivers and get them off the road. Herb Hill, a chemistry professor at Washington State University, and his colleagues are trying to develop a hand-held device that police officers can use to detect THC in breath. Preliminary field testing with 30 human subjects this spring established that the device works. Much more testing is ahead to look at potential variations among gender, race, body types and amount of use. “In the beginning at least this would not be used as evidential information,” Hill explained. “It would be used as screening information to help the officer say he should take a blood sample now.”