Prosecutors need proof medical marijuana users actually impaired for DUIs

Voters will decide if marijuana should be legal for recreational use and regulated in a manner similar to liquor.

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Voters will decide if marijuana should be legal for recreational use and regulated in a manner similar to liquor.

PHOENIX – Medical marijuana users cannot be convicted of driving while under the influence of the drug absent proof that they were actually impaired, the state Court of Appeals ruled Thursday.

In a major setback for prosecutors, the judges pointed out that Arizona, unlike some other states, has no law which spells out that at a certain level of tetrahydrocannabinol in the blood a person is presumed to be impaired. That is the psychoactive ingredient in marijuana.

“And, according to evidence here, there is no scientific consensus about the concentration of THC that generally is sufficient to impair a human being,’’ appellate Judge Diane Johnsen wrote.

What that means is each and every case where prosecutors charge a medical marijuana user with breaking the law requires expert testimony to show that particular individual was impaired at that particular level of THC.

This case involves Nadir Ishak who was stopped by police in Mesa one evening in 2013 after the officer said he saw the vehicle drift out of its lane. The officer testified that Ishak had admitted to smoking marijuana that morning, that his eyes were bloodshot and watery, and that during a field sobriety tests he experienced “body tremors and eye tremors.’’

Ishak was charged with driving while impaired to the slightest degree and a separate charge of driving with marijuana in his body. Jurors acquitted him of the first charge but convicted him of the second.

Johnsen said Ishak was denied a fair trial when the city court judge refused to allow him to tell jurors he had a state-issued card allowing him to use the drug legally. She said that would have provided evidence to the jury that Ishak was legally entitled under the 2010 Arizona Medical Marijuana Act to use the drug and have it in his system.

Potentially more significant, Johnsen, writing for the 2-1 majority, said the trial judge also erred in ruling that it was up to Ishak to prove he was not impaired, even to escape the charge of driving with marijuana in his body.

What voters approved in 2010 spells out that being a legal marijuana user does not excuse someone from being charged with driving under the influence of the drug. But it also says that a patient cannot automatically be considered under the influence of marijuana “solely because of the presence of metabolites or components of marijuana that appear in insufficient concentration to cause impairment.’’

The Arizona Supreme Court already has ruled that the mere presence of metabolites – the chemical compounds caused the breakdown of marijuana in the body – is insufficient by itself to prove impairment. That’s because those chemicals can remain in the body for days or weeks afterwards.

In this case, however, the court records show that Ishak had a concentration of 26.9 nanograms per milliliter of tetrahydrocannabinol, the psychoactive ingredient in marijuana.

Mesa city prosecutor Craig Jones argued that the 2010 law requires medical marijuana cardholders who are arrested to prove through expert testimony that the amount of THC in their blood is insufficient to cause impairment “in people generally’’ or “in any person.’’ He said it’s irrelevant whether the specific defendant was actually impaired.

But Johnsen said that’s not how the law works.

“Nothing in the statute ... requires a cardholder to present expert testimony (or precludes a cardholder from offering non-expert testimony) on the question of whether the cardholder was impaired due to THC,’’ she wrote.

“Further supporting this conclusion is the reality that, at present, there is no presumptive impairment limit established by (Arizona) law,’’ the judge wrote. By contrast, Colorado statutes say anyone with a THC above 5 nanograms is presumed impaired.

And Johnsen said in this case there was no foundation for the state’s expert to testify that a THC level of 26.9 nanograms would cause impairment in Ishak.

On the other side of the equation, Ishak’s own expert said there is “no consensus’’ about the concentration of THC that causes impairment. The expert did testify that 26.9 is “a high number and it can impair some people, but I can’t tell you that number ... will impair all people.’’

That ruling was not unanimous.

Appellate Judge Randall Howe said he reads the statute and case law to give medical marijuana cardholders an “affirmative defense’’ they can present at trial. He said that means it is up to the person arrested to prove not only that he or she is authorized to use marijuana for medical purposes, but that the concentration of the drug was “insufficient to cause impairment.’’

“The defendant bears the burden of proof on the defense,’’ Howe wrote. And he said Ishak did not show, either in cross-examining the state’s expert or presenting his own, that his THC concentration did not leave him impaired.

Thursday’s decision is the latest in a string of appellate court rulings which have limited the ability of prosecutors to bring various charges against medical marijuana patients. These range from limiting the kind of evidence that prosecutors can use to bring drugged-driving charges to requirements for law enforcement officers to give back drugs taken from legal users.

And it comes just two days after another division of the appellate court slapped down efforts by Maricopa County Attorney Bill Montgomery to use the federal ban on marijuana to block the necessary permits for a medical marijuana dispensary.