Dear Editor: Kudos to contributor Dave Glomp for highlighting that Wisconsin’s zero-tolerance per se statute for marijuana, which criminalizes the operation of a motor vehicle by anyone with any detectable amount of cannabis in their system — irrespective of whether they are actually impaired — is not evidence-based and could result in the inadvertent prosecution and conviction of non-impaired drivers (“Wisconsin should proactively set laws for driving under marijuana influence,” Jan. 16). This is because both THC, marijuana’s primary active ingredient, and its byproducts (metabolites) are detectable for periods of time extending well beyond any reasonable period of impairment. THC, for example, may be detectable in blood for up to seven days in some consumers, while its primary metabolite carboxy-THC may be present in urine for several months.
This is not to say that acute cannabis intoxication cannot influence driving behavior or to imply that driving while impaired by marijuana should not to be a traffic safety violation. Of course, driving under the influence in all instances ought to be — and is — criminalized, regardless of whether the intoxication is due to opioids, benzodiazepines or any number of substances that can alter driving performance. But in cases involving other substances, police must have demonstrable evidence that a driver is impaired; the outcome of the prosecution cannot be based solely upon the detection of the substance in their blood and urine. This same standard ought to apply to cannabis.
Deputy director, National Organization for the Reform of Marijuana Laws (NORML)