Presence Of THC Metabolite Alone Not Evidence Of Driver Impairment, Court Says

Thursday, 28 July 2005

Traverse City, MI: The presence of cannabis' primary metabolite, THC-COOH, is insufficient evidence of impairment to warrant a conviction under the state's "zero tolerance" per se drugged driving law, according to a recent ruling by the Michigan Court of Appeals. The decision upholds a trial court ruling that found the "prosecution must prove that the presence of a controlled substance in a defendant's body is proximate cause of an accident resulting in death or serious injury" in order for the defendant to be guilty of violating the state's two-year-old drugged driving statute.

Michigan is one of ten states that have enacted so-called "zero tolerance" drugged driving laws. Under Michigan's law, it is a criminal offense for an individual to operate a motor vehicle with any detectable level of a Schedule I substance present in his or her bodily fluids. (In six states - Arizona, Georgia, Illinois, Indiana, Nevada, and Utah - individuals may be criminally prosecuted if they operate a vehicle with any level of a Schedule I drug or drug metabolite in their system. Three additional states - Nevada, Pennsylvania, and Virginia - have enacted per se drugged driving standards, prohibiting individuals from operating a motor vehicle if they have levels of Schedule I drugs present in their body above a specific threshold.)

In the case before the court, the defendant tested positive for the presence of the THC metabolite THC-COOH (a non-psychoactive compound produced during the body's biological process of converting THC into a water soluble form), but maintained that she was unimpaired at the time of her accident. The prosecution argued that it was not required under Michigan's "zero tolerance" drugged driving law to establish that the defendant's impairment caused the accident, only that she had an illegal substance present in her body. The appellate court upheld the trail court's ruling, affirming that marijuana's metabolite is neither psychoactive nor classified as an illegal substance, and that the prosecution had failed to prove a causal relationship between the presence of a controlled substance in the defendant's body and the accident.

Michigan's Supreme Court had previously held that the legislature did not "intend to impose strict liability on an individual" involved in a driving-related accident, the appellate court determined. Rather, the legislature's intent is to criminally punish only individuals whose impaired driving causes another person's injury.

"The defendant's purposeful operation of [a] vehicle while under the influence must have been a substantial cause of the victim's death," the court of appeals determined. It further found that the "legislature did not intend to include [the cannabis metabolite] as a Schedule I controlled substance because it has no pharmacological effect on the human body ... and its levels in the blood correlates poorly, if at all, to an individual's level of THC-related impairment."

As a result, the appellate court ruled, "Imposing a penalty on a driver when the ... accident would have occurred regardless of that intoxication would ... fail to serve the purpose of the statute."

Prosecutors have not announced whether they intend to appeal the court's decision to the Michigan Supreme Court.

For more information, please contact either Paul Armentano or Keith Stroup of NORML at (202) 483-5500. A comprehensive breakdown of state drugged driving laws appears in NORML's report, "You Are Going Directly to Jail: DUID Legislation: What It Means, Who's Behind It, and Strategies to Prevent It," available online at: