Unlike alcohol, determining whether or not someone is currently under the influence of marijuana is tricky; police are not equipped with mobile devices that can give them readings one way or the other. Currently, if an officer suspects that a driver is “high,” the suspect will have to submit to a blood analysis to determine the concentration of marijuana in the bloodstream. 5 nanograms of active THC per milliliter of blood was set as the legal limit under Initiative 502; anyone testing above 5 is automatically determined to be impaired.
At Washington State University, researchers are developing a breath test for THC, the psychoactive ingredient in marijuana, according to The Seattle Times. In Washington, the need for a standardized mobile test that officers can use to determine THC levels is paramount, perhaps the only sure way to dissuade drugged-driving.
Legalization in Washington has brought with it a surge of drivers testing positive for THC. In 2013, the Washington State Toxicology Laboratory reported that 25 percent of all tested blood samples taken from drivers suspected of driving under the influence, tested positive for active THC. In 2012, the year that legalization passed, only 18.6 percent of blood samples tested positive.
Washington State University chemistry professor Herbert Hill and WSU doctoral student Jessica Tufariello believe they can re-purpose devices, like the ones used by airport security and customs agents to detect drugs and explosives, into mobile units that can test one’s breath for THC. According to Hill, preliminary devices probably won’t be able to pinpoint the level of THC in the body, just whether or not THC is present. However, Hill believes that such a device could help law enforcement determine whether to arrest a suspected impaired driver for further testing.
“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.”