Driving under the influence of marijuana is illegal. Yet, with states having different criteria as to what constitutes driving under the influence of drugs (DUID), marijuana consumers need to be familiar with what “under the influence” really means. Unlike the nationally recognized standard for drunk driving (0.08% blood alcohol concentration, or BAC, in every state except Utah), there is no comparable nationwide standard for drug impairment. Additionally, limitations of drug-detecting technology and the fact that THC levels in the bloodstream vary depending on individual factors (such as metabolism and frequency of use) complicate the enforcement of DUID laws.
The majority of states, including California, Texas, Florida, and New York, have impairment-based DUID laws, which “require the driver to be under the influence of or affected by THC” (NCSL, 2024). This goes beyond the THC levels in the bloodstream and focuses on whether the driver is impaired. Several states, including Arizona, Pennsylvania, and Michigan, have zero-tolerance laws; the law “prohibits driving with any amount of THC and/or its metabolites in the body” (NCSL, 2024).
A small group of states, including Washington and Nevada,have specific per se laws, whereit is illegal to drive over the legal limit of detectable THC. These limits generally range from 2 to 5 nanograms per milliliter (ng/ml) of blood, and “once a person is shown to have reached or surpassed the legal limit, that person will be considered impaired by law” (NCSL, 2024). However, these limits are problematic as, depending on factors such as tolerance and metabolism, THC affects individuals differently. Colorado has a permissible inference law, meaning the jury, or a judge in a bench trial, is allowed to assume the driver was under the influence if the THC in their blood is at 5 ng/ml or above. However, unlike per se laws, drivers can raise affirmative defenses to …
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Author: Coco Kesselman / High Times
