“The medical marijuana is actually for the caregiver,” my dad explained. I did not know that. “Everyone knows that,” he assured me, having discovered as much in his support group. My mother was dying of lung cancer, and in the full throes of cancer pain, helped very little by Vicodin, Oxycontin, or even morphine. My dad had been awake most of the night for weeks, caring for his wife of 51 years. Pain has a sound, and he heard it. All night. This was back in the early days of California’s Proposition 215, the Compassionate Use Act of 1996. Medical marijuana. I knew little about it, and assumed its use was limited to patients with severe cancer pain, the symptoms of AIDS, and other diseases that were, or threatened to be, mostly terminal.

No one in that house was driving around under the influence of marijuana, medical or otherwise.

Today, 23 states and the District of Columbia have enacted laws to legalize medical marijuana. In Arizona, the law allows qualifying patients to obtain marijuana from a registered dispensary, upon receipt of an identifying card, obtained with a physician’s written certification that the patient has a debilitating disease. There is a list of debilitating medical conditions that qualify for medical marijuana, and public hearings for those who want to petition to add to the list of conditions. Specific information is available at http://www.azdhs.gov/medicalmarijuana/faqs/index.php . The list includes people who are able, or who think they are able, to drive around, after ingesting medical marijuana.

On October 21, 2014, the Court of Appeals concluded that Arizona’s Medical Marijuana Act (AMMA) does not give an authorized medical marijuana user immunity from prosecution when he drives under the influence. A.R.S. § 28–1381(A)(3) criminalizes driving while there is any prohibited drug or its metabolite in a person’s body. Travis Lance Darrah was an authorized medical marijuana user when he was arrested in December 2011 and charged with two counts of DUI in violation of A.R.S. §28-1381. His blood contained 4.0 ng/ml of delta -9-tetrahydrocannobinol, an active component of marijuana.

The trial court precluded evidence that Darrah possessed a medical marijuana card at the time of his offenses, and a jury found him guilty under A.R.S. §28-1381(A)(3)(presence of marijuana or its metabolite). The jury acquitted him of the charge under A.R.S. §28-1381(A)(1)(impairment). Darrah asked the reviewing court to set aside his DUI conviction based on A.R.S. §36-2802(D), which provides that a registered qualifying patient shall not be considered to be under the influence of marijuana solely because of the presence of metabolites or components of marijuana that appear in insufficient concentration to cause impairment. Darrah argued that this provision manifests the intent of the AMMA to make all authorized medical marijuana users immune from prosecution unless they drive while impaired.

The Court of Appeals found that nothing in the plain language of §36-282(D) or elsewhere in the AMMA supports Darrah’s interpretation of the statute. The Court said that if Arizona voters had intended to completely bar the State from prosecuting authorized marijuana users under §28-1381(A)(3), they could have done so by using specific language. The Court found further that Darrah’s interpretation contravenes the Arizona Supreme Court’s determination earlier this year that, despite the legality of marijuana for medicinal purposes, prosecutors can charge legal users under A.R.S. §28-1381(A)(3) because that statute does not require the state to prove that the marijuana was illegally ingested. Accordingly, the AMMA does not bar prosecution for DUI.

My dad agrees: “Marijuana,” he says, “impairs one’s judgment and sense of time and space and can be dangerous when driving,” but “when properly used for relief of pain and nausea from chemotherapy, it has its place.” My dad got the pills from a retired doctor in his cancer support group who described them as “synthetic marijuana.” They reportedly had no effect on the caregiver.