A team at Washington State University is developing a breath test to test for marijuana to help law enforcement determine whether a driver is under the influence of marijuana. Currently no device exists to test for marijuana impairment using a breath sample. Officers and prosecutors have to instead rely on blood tests to determine how much active THC is present in a driver’s blood. Initially, the marijuana breath test probably won’t be able to pinpoint the level of THC in the body; it will only tell officers that some active THC is present.
According to WSU chemistry Professor Herbert Hill, existing technologies that are used by airport security to detect drugs can be re-purposed to test breath for THC. The handheld device will use a technique called ion mobility spectrometry to detect THC in someone’s breath.
“We believe at least initially that it would lower the false positives that an officer would have,” Hill said. “They would have a higher level of confidence in making an arrest.”
Officers would still have to obtain follow-up-test results to use as evidence in court, just as they do after a positive preliminary breath test for alcohol impairment in a DUI arrest.
Hill said he and his research team plan to finish laboratory tests with a prototype marijuana breath test this year, then start testing human breath between January and June 2015.