Last month, the Arizona Supreme Court ruled 4 to 1 that laws designed to handle driving under the influence (DUI) of alcohol could not be applied directly to marijuana because of the way the drug interacts with the bloodstream.
Under DUI laws, a person is automatically guilty of a crime if his blood alcohol content is 0.08 percent, when measured after driving, regardless of whether he was actually impaired behind the wheel. The drunk driving standard creates issues with stoned driving, because there are two distinct byproducts of marijuana use in the bloodstream, known as “metabolites,” but only one of them causes impairment.
On December 11, 2010, Hrach Shilgevorkyan was pulled over for allegedly speeding and making an unsafe lane change at around 10:30pm. The arresting officer performed field sobriety tests during which Shilgevorkyan admitted he had smoked “some weed” the previous night.
Shilgevorkyan gave a blood sample just after midnight which revealed the presence of the nonpsychoactive metabolite of marijuana known as “carboxy-THC.” This substance can linger in the bloodstream one month after smoking a joint and has no effect on the brain.
The substance that produces the high is “hydroxy-THC” which the body’s metabolism breaks down into carboxy-THC, according to Brandon Nabozney, the expert witness who testified at the trial. Shilgevorkyan argued that the statute, which refers to “metabolite” in the singular, must only refer to hydroxy-THC because that is the only substance that causes impairment. The high court justices agreed that the statute’s wording was ambiguous and should be interpreted in a way that does not lead to an absurd result, which is what would happen if prosecutors were allowed to implement a zero-tolerance reading of the law.
“This interpretation would create criminal liability regardless of how long the metabolite remains in the driver’s system or whether it has any impairing effect,” Justice Robert M. Brutinel wrote for the majority. “For example, at oral argument the state acknowledged that, under its reading of the statute, if a metabolite could be detected five years after ingesting a proscribed drug, a driver who tested positive for trace elements of a non-impairing substance could be prosecuted.”
The court was uncomfortable criminalizing legal conduct, as Arizona voters legalized medical marijuana use in a 2010 referendum. The majority also noted that certain legal drugs can share a metabolite with an illegal drug, which causes a problem with the drugged driving statute that automatically criminalizes the presence of the metabolite in the bloodstream.
“Because Section 28-1381(A)(3) does not require the state to prove that a substance discovered in a driver’s body is actually metabolized from a prescribed drug, the state’s interpretation would permit prosecution if the discovered substance is a metabolite of a prescribed drug even if the prescribed drug was never ingested,” Justice Brutinel wrote. “These results are absurd and make the state’s argument untenable.”
The Supreme Court majority declared that the legislature must have meant that any amount of the impairing hydroxy-THC was a criminal act, not the carboxy-THC substance that lingers in the bloodstream for thirty days.
Click the link below to read the supreme Court Ruling.