Arizona Supreme Court rules on medical marijuana in DUI cases

A medical marijuana user's card is not a get-out-of-jail-free card if you are charged with DUI.

But it can be used as a defense at trial, the Arizona Supreme Court ruled Friday.

It comes down to conflicting Arizona statutes. The Arizona Medical Marijuana Act (AMMA), which was passed as a citizens' initiative in 2010, says that licensed medical marijuana users cannot be prosecuted for marijuana useif they stay within the parameters of the statute. But state laws on driving under the influence (DUI) forbid driving while impaired by marijuana, which extends even to the presence of metabolites in the bloodstream — that is, the residue of drug that remains in the body even after the person is no longer impaired.

In the case before the Arizona Supreme Court, two persons were convicted of DUI in Arizona municipal courts. (Most DUIs are misdemeanor charges and therefore tried in municipal courts or justice courts.) The defendants were not allowed to use their medical marijuana cards as a defense, so they appealed, first to the Maricopa County Superior Court, and then the Arizona Court of Appeals, both of which affirmed the municipal court verdicts.

In Friday's opinion, authored by Chief Justice Scott Bales, the court ruled that the marijuana card did not grant immunity.

But, Bales wrote, "The patient may establish an affirmative defense to such a charge by showing that his or her use was authorized by the AMMA..."

There's a big catch: The defendant has to prove "by a preponderance of the evidence" that the metabolite was at a level that no longer caused impairment. And as the defendants said in their argument, "there is no commonly accepted threshold for identifying such concentrations."

It was not the first time the court ruled on the question, however. In 2014, the justices ruled that to equate the mere presence of metabolites to impairment was "absurd." And that ruling mentioned the possibility of a legal marijuana user under AMMA who would be prosecuted for the presence of metabolites in his or her body, essentially setting the stage for Friday's opinion.

The ruling did not help the defendants in question, however. The court ruled that they did not offer any evidence to show that the concentration of drugs in their systems was "insufficient to cause impairment." Their convictions were upheld.

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Mason Tvert, director of communications for the Marijuana Policy Project, a national pro-marijuana organization, pointed out that driving while impaired, no matter the substance, has always been illegal.

Driving while under the influence of marijuana is likely to be a point of contention in the Regulate Marijuana Like Alcohol campaign to legalize cannabis for recreational use in Arizona. That campaign has gathered about half the number of signatures needed to put the initiative on the 2016 ballot, Barrett Marson, a spokesman for that campaign, said.

More than 80,000 Arizonans have medical marijuana cards.

“We should have laws that prohibit driving while impaired with marijuana that are evidence-based and ensure people are actually punished if they’re actually impaired,” Tvert pointed out. “Right now, there’s still a need to determine what the best testing is. It can be based on combined testing – blood testing right now is the most effective testing when it comes to determining how much active THC (the active chemical in marijuana) is in someone’s body,” he said, referring to the active ingredient that causes a high.

Tvert pointed out the mere presence of THC in the body doesn’t mean drivers were necessarily driving while impaired since the chemical stays in the body long after they used the drug.

Melissa DeLaney, a spokeswoman for Arizonans for Responsible Drug Policy, a campaign opposing legalization in Arizona, said the ruling was a win for public safety.

"This was absolutely the right call," DeLaney said. "Impairment is impairment, regardless of circumstance. Just because it's legal for a person to drink alcohol, doesn't mean he or she has the right to drive drunk. A medical marijuana card is no different and should never be considered a free pass to make irresponsible decisions."

But Maricopa County Attorney Bill Montgomery, a fervent crusader against marijuana, took further issue.

"While the result is correct, the court fails to avoid treading where it lacks the competence or authority to legislate," Montgomery said. "There is no per sé THC limit or recognized consistent levels of impairment for various categories of users in statute and the court fails to restrain itself from further mischief following its rewrite of (the statute), now requiring a new type of drug metabolite. Today’s ruling also conflates impairment (...) with presence of drug. This is just the latest example of how poorly drafted the AMMA is."