The Lawletter Vol 39 No 5
Arizona is one of seven states that make it unlawful for a driver to be in actual physical control of a motor vehicle while there is a proscribed drug or "its metabolite" in the operator's body. Ariz. Rev. Stat. § 28-1381(A)(3). (The other six zero-tolerance jurisdictions are Delaware, Georgia, Indiana, Minnesota, Pennsylvania, and Utah. Joshua C. Snow, The Unconstitutional Prosecution of Controlled Substance Metabolites Under Utah Code § 41-6a-517, 2013 Utah L. Rev. OnLaw 195, 212 n.14 (2013).) In State ex rel. Montgomery v. Harris, 322 P.3d 160 (Ariz. 2014), the Supreme Court of Arizona was asked to determine whether the phrase "its metabolite" includes Carboxy-Tetrahydrocannabinol ("Carboxy-THC"), a nonimpairing metabolite of marijuana, which is a drug proscribed by statute. The court concluded that it does not.
In Montgomery, the driver was stopped for speeding and making unsafe lane changes. After admitting to smoking some "weed" the night before, the driver voluntarily submitted to a blood test that revealed Carboxy-THC in his blood. He was charged with driving under the influence of a drug, in violation of section 28-1381(A)(1), and driving while a metabolite of a proscribed drug was in his body, in violation of section 28-1381(A)(3). The justice court dismissed the charge based on the presence of "its metabolite," and the State voluntarily dismissed the driving-under-the-influence charge. The superior court affirmed the justice court, but the court of appeals reversed, finding that the statute included the metabolite Carboxy-THC and that inclusion was not overbroad. State ex rel. Montgomery v. Harris ex rel. County of Maricopa, 301 P.3d 580 (Ariz. Ct. App. 2013). The state supreme court vacated the opinion of the court of appeals and affirmed the dismissal of the "its metabolite" charge, with one justice dissenting.
The court found "its metabolite" to be ambiguous because it could mean all of a proscribed drug's metabolites, some of its metabolites, or only metabolites that cause impairment. The driver argued that the phrase referred to only Hydroxy-THC, the initial product of the metabolism of THC. The State insisted that the statute referred to all metabolites, including the nonimpairing Carboxy-THC, which was tested for. Significantly, the impairing Hydroxy-THC does not remain in the blood for very long and quickly converts to Carboxy-THC, which is why the State tests for Carboxy-THC but not for Hydroxy-THC. Carboxy-THC, on the other hand, can remain in the body for as many as 28 to 30 days after the ingestion of marijuana.
Looking to the legislative history, which demonstrated an intent to prevent impaired driving, the court concluded that "its metabolite" is limited to metabolites capable of causing impairment. To hold otherwise could lead to the absurd result that a driver could be found guilty regardless of how long the metabolite remained in his or her body or whether it had an impairing effect. Furthermore, given that Arizona legalizes marijuana for medicinal purposes, the State's overinclusive reading could criminalize legitimate use after the impairing effects have worn off. Finally, a broad reading of "its metabolite" could allow the prosecution of an individual who drives after ingesting a legal substance that shares a nonimpairing metabolite with a proscribed substance.
This decision in Montgomery hardly leaves Arizona without the ability to prosecute those driving under the influence of proscribed drugs. The prosecution may still establish criminal liability by evidence of impairment. Moreover, as the State admitted, it is possible to test for the impairing Hydroxy-THC, and the State may choose to do so. The decision merely serves to ensure that only those who are actually driving while impaired can be convicted.