Arizona Supreme Court Rules on Medical Marijuana and DUI

When the Arizona Medical Marijuana Act was passed in 2010, it represented good news for those who wanted to use pot to alleviate various medical conditions. The Act says, in effect, that you can’t be prosecuted for using marijuana provided you stay within the requirements of the statute. So far, so good. Then along comes the Arizona law regarding driving under the influence, and an apparent discrepancy was noted.  The DUI law, in particular A.R.S. 28-1381A3, says that it is unlawful to drive while there is any one of hundreds of drugs in your body, including “metabolites” of any of those drugs. One of those drugs, of course, is marijuana.

What the citizens of Arizona were left with was one law that said they could use marijuana legally with a valid medical marijuana card, and another that said the use could lead to a DUI charge. The apparent inconsistency was resolved by the Arizona Supreme Court last week. The essential question was whether you could be convicted of DUI based solely upon the presence of a cannabinoid metabolite in your body, absent any evidence of being “under the influence”, that is, evidence that you were impaired. The issue is particularly important with marijuana, since the metabolite can remain in your system for days, long after it would cease to have any effect on your ability to operate a motor vehicle.

The Supreme Court reviewed two cases on the subject, both of which involved DUI charges where the defendants were not permitted to raise the Medical Marijuana Act as a defense at their DUI trials. Both were convicted based upon the presence of a metabolite of marijuana in their bodies. The court ruled, first, that having a valid medical marijuana card did not in and of itself provide immunity for prosecution on a DUI drug charge. But the court went on to rule that having a valid medical marijuana card can be used as an affirmative defense. In order to prevail at your DUI trial, however, you have the burden of proving (by a preponderance of the evidence) that the concentration of the metabolite in your system was insufficient to cause impairment.