Can Tolerance Be Used as a Defense for a Marijuana DUI?

Courtesy of Godoy Medical Forensics


Medical marijuana is becoming more and more visible as it makes its way through the various steps of legalization and post-legalization changes and amendments. The ability to defend a person charged with DUI of medical marijuana poses new challenges to defense attorneys everywhere. A good understanding of what medical marijuana is prescribed for and the side effects—both desired and inevitable—is necessary in order to defend a person’s right to function in society while recovering from a painful and sometimes terminal disease. One defense strategy might be to argue that a high tolerance due to the chronic ingestion reduces the effect of the medication on the brain.

California is one of 14 states that have legalized marijuana for medical uses. The federal government, however, still holds marijuana illegal for any purpose. The law in California became effective November 6, 1996, and is allowed only in certain quantities and for certain conditions. According to CNBC, those conditions are “AIDS, anorexia, arthritis, cachexia, cancer, chronic pain, glaucoma, migraine, persistent muscle spasms, including those associated with multiple sclerosis, seizures associated with but not limited to epilepsy, severe nausea” (CNBC, 2010).

The first factor is, of course, to determine that the person was using the marijuana according to the state’s guidelines. Once that is determined to be valid, there are two factors that can affect the outcome of a DUI charge in regards to medical marijuana: potential side effects and the driver’s tolerance to them. The known side effects of marijuana include light-headedness, paranoia, anxiety, and loss of coordination. External physical symptoms include tachycardia and dilation of the pupils. Therefore, a field sobriety test (FST) may come out as abnormal if administered correctly. The desired side effects when used for medical purposes include decreased nausea and vomiting, increased appetite, and general analgesic effects (pain relief).

Users of medical marijuana may, however, not be susceptible to the side effects that affect their ability to drive if they have been taking the marijuana consistently for a period of time. One study indicated that tolerance can begin after only four to five days and that the tolerance applies to some, but not all, of the side effects and symptoms. (Jones, Benowitz, & Herning, 1981).

The idea is that just because someone is tolerant to some of the side effects does not necessarily mean that (1) they will increase the amount they ingest; or (2) that they are not receiving the desired effect of the medication. According to the Le Dain Cannabis Report, “[s]elf-administration of increased doses would not ordinarily be expected unless tolerance had developed to those specific aspects of the drug reaction which were reinforcing or rewarding its use. Tolerance or adaptation to some effects of a drug might occur independently from those responses which are sought by the user.” (Canadian Government Commission of Inquiry into the Non/Medical Use of Drugs, 1972)

In summary, as the policies and laws change in regards to the use of medical marijuana, we must keep ourselves current on potential defenses for charges relating to and including the intoxication of marijuana in persons who are permitted to use marijuana for medical purposes. This not only applies to the laws themselves, but to the potential uses, side effects, and symptoms of marijuana. More studies will be coming out to support and hinder our theories on tolerance. The potential of using tolerance as a defense for a DUI charge for a medical marijuana user may include that he or she had a tolerance to the less desirable side effects of the medication, but was still receiving the therapeutic benefit of the drug.