Court Ruling: Marijuana Users Must Show Impairment to Face AZ DUI Penalties

The Arizona Court of Appeals has ruled that an individual’s driver’s license cannot be suspended solely due to the presence of THC metabolites in their bloodstream unless there is evidence of impairment while driving. This decision upholds a provision from a marijuana legalization law passed by voters in 2020.

The case involved Aaron Kirsten, who was pulled over for speeding in Sedona in October 2022. During the stop, an officer noted his bloodshot eyes and slurred speech. Although Kirsten declined a field sobriety test, a breathalyzer test revealed a blood alcohol content (BAC) of 0.083, slightly above the legal limit. He was subsequently arrested.

While in custody, Kirsten consented to a blood draw. The analysis indicated his BAC was 0.063, below the threshold allowed under state law. However, the Department of Public Safety (DPS) also found metabolites of THC in his blood, leading the Arizona Department of Transportation (ADOT) to impose a 90-day license suspension.

During the appeal process, Kirsten testified that he had not consumed THC within 24 hours of his arrest, arguing that any effects had dissipated. A family member, a nurse and chiropractor, corroborated this, explaining that THC metabolites can remain in the bloodstream for weeks after the substance is used.

The administrative law judge, however, deemed the timing of Kirsten’s marijuana use as “irrelevant,” siding with ADOT’s stance that a license suspension could occur without the need to prove current impairment by THC.

Kirsten’s subsequent appeal to the Maricopa County Superior Court reaffirmed the administrative judge’s ruling. Yet the appellate court found both rulings had misinterpreted the laws formulated by voters concerning marijuana use.

Specifically, the court clarified that existing laws protect individuals from sanctions related to legally permitted marijuana use unless they are impaired while driving. Driving is classified as a privilege under Arizona law, thus protections extend to driving rights of those with THC metabolites in their system.

The court highlighted that Proposition 207 allows for penalties only when a driver is impaired “to even the slightest degree” due to marijuana consumption, a condition that did not apply in Kirsten’s case. The unanimous three-judge panel emphasized that unimpaired driving after marijuana use cannot be penalized.

In addition, the appeals court rejected the state’s argument for license suspension based on alcohol impairment, noting that this position was not pursued during the proceedings. Judge Andrew Jacobs stated, “The State waived that position by choosing not to pursue it.”