Drunk driving is pretty easy to spot. If someone is swerving or driving at dangerously high speed, a cop or highway patrol officer can easily ask a driver to blow into a breathalyz or ask them to stand on one leg, touch their nose and count backwards. Testimony from officers who witnessed failed sobriety tests has influenced countless DUI convictions. But what do officers do if they suspect a driver is stoned? Can the same tests determine if a driver is high?
A number of defense attorneys have spent a lot of time in court arguing that they cannot. While the science behind a Breathalyzer is readily available, similar tools have not been developed to determine how recently - or how intoxicated - a person is from marijuana.
According to NPR, Massachusetts defense attorney Rebecca Jacobstein argued just that in a case in front of her state’s high court. "If there's reliable science, reliable science gets to come in," Jacobstein argued. "It's just that unreliable science does not."
And while officers can test for marijuana in a driver’s bloodstream or hair follicles, those tests can only determine presence, and not time taken or intoxication. And as anyone who’s sweated out a drug test knows, marijuana is fat-soluble, and can stay in a person’s system for up to a month after they’ve smoked, vaped or ingested it.
Enter Michael Milburn, a psychology professor at the University of Massachusetts who thinks he has the solution cops, lawmakers, and drivers are looking for. Milburn has developed an iPad app he calls Druid, that features a series of tests that he says are specifically designed to test levels of marijuana intoxication.
Milburn says that Druid tests stoner-symptoms like the inability to divide attention effectively or recognize time passing, as well as slow reaction times. One example is a test that asks the subject to keep track of disappearing shapes.
"When the circle flashes on the screen, you hit the screen where you saw the circle appear," Milburn explained to NPR. "If a square appears, [you] hit the white oval on the top of the screen. I figure someone who's stoned is gonna go 'Alright, was it the circle or the square?' "
Druid currently has four tests, including one that would keep highway patrolmen comfortable, asking drivers to stand on one leg like a classic DUI sobriety test.
The app though, will keep track of every shake and wobble, and paired with the memory and quickness tests, will give a sobriety score much like a Breathalyzer.
With the technology available, the tests won’t be a walk in the park. "If you're going to be driving a car, you should be able to perform at a fairly high level.” Milburn said.
Druid is still in the beginning stages of development, and experts are still looking into tests that can effectively determine how recently someone has smoked marijuana. However, it probably won’t be long before officers around the country have separate tests to determine if drivers are potentially drunk or stoned.