As of the 2016 election, medical marijuana is now legal in 29 states as well as the District of Columbia. Arizona is among the states that have legalized marijuana for medical purposes, passing the law in 2010. However, driving while under the influence of marijuana remains illegal. If a driver is too impaired to be behind the wheel, even after taking a substance that was legally prescribed to them, that driver can be charged with a DUI.

The Arizona Court of Appeals recently dealt with a case concerning medical marijuana. The case dealt with what defenses a person holding a medical marijuana card could raise after being charged with a DUI. In the case the defendant, Nadir Ishak, was pulled over after a police officer saw him swerve into another lane. He was ultimately charged with two counts: "driving under the influence while impaired to the slightest degree . . . and driving with marijuana or its metabolite in his body." The State sought to block evidence that the defendant held a medical marijuana card and Ishak objected to this motion "arguing the jury should not be misled 'into thinking that it's actually illegal for him to ingest' marijuana." However, his motion was denied. The appellate court noted that the motion was denied prior the Arizona Supreme Court deciding the case of Dobson v. McClennen.

At trial the officer testified about his encounter with the defendant and both the State and Ishak called witnesses to testify about the amount of THC that was found in Ishak's blood. Ishak was found guilty of one of the charges -- driving with marijuana or its metabolite in the body. He then appealed to the superior court after the Supreme Court had decided Dobson but the court found that not allowing evidence of Ishak's medical marijuana card was harmless error.

The Court of Appeals then took up the case and disagreed with the lower court's decision. The court stated that the law was concerned with just the metabolites of marijuana that were "capable of causing impairment." In the recently decided Dobson case, the Supreme Court had created an affirmative defense for those who possessed medical marijuana cards. The high court held that "when charged with violating § 28-1381(A)(3), a 'patient may establish an affirmative defense to such a charge by showing that his or her use was authorized by the AMMA . . . and that the marijuana or its metabolite was in a concentration insufficient to cause impairment.'" The appellate court stated that under Dobson, the lower court "erred by precluding Ishak from offering evidence to support the premise of a cardholder's affirmative defense."

The State argued that not allowing evidence of a marijuana card did not prejudice Ishak because he did not offer evidence from an expert that that the THC concentration that was found in his blood was insufficient to impair "any human." The Court of Appeals found this argument unpersuasive stating that the affirmative defense only required the defendant to show that he or she was not impaired, not that no human could be impaired at the levels found in his bloodstream. In addition, the court found that expert testimony was not required because the testimony of the defendant, as well as other witnesses, would be relevant depending on the circumstances and there was no currently legal presumptive level of impairment in the state or a "scientific consensus about the concentration of THC that generally is sufficient to impair a human being."

The court then vacated Ishak's conviction and remanded the case. You can read the court's opinion here.