State Supreme Court Changes Marijuana DUI Regulations

Apr 22, 2014

Motorists who smoke marijuana can’t be charged with driving while impaired without actual evidence they are affected by the drug, the state Supreme Court ruled today. Arizona Public Radio’s Howard Fischer explains.


The law spells out that it is evidence that someone has been driving under the influence of marijuana if a blood test turns up evidence of Carboxy-THC. This is a metabolite of marijuana, something produced by the body as it breaks down the psychoactive elements of the drug. But, in the case before the high court the prosecution’s own expert witness conceded that metabolite does not cause impairment. So, Justice Robert Brutinel, writing for the majority, said evidence of Carboxy-THC in a blood sample, absent more, cannot be used to sustain a conviction. The ruling drew a sharp reaction from Maricopa County Attorney Bill Montgomery who said it will lead to more people driving while still high — and more accidents.

“By ruling the way that the court did, we’re actually inviting people to a kind of game when all active metabolites that would lead to impairment might be out of their system. And, given the fact that people’s judgment is impaired to begin with when they’re under the influence of marijuana, there’s no real way for them to know,” Montgomery said.

But, Brutinel said following Montgomery's logic would make criminals out of people who legally can use marijuana for medical reasons. That’s because Carboxy-THC can remain in the body for four weeks after use, meaning choosing between driving and getting needed medication.