The pitfalls of per se thresholds in accurately identifying acute cannabis intoxication at autopsy


Some laws in the United States define cannabis-impaired driving criteria using various per se language that uses specific concentrations of various cannabinoid compounds to establish driving-under-the-influence (DUI). We hypothesize that there will be decedents whose postmortem toxicology profiles would be considered indicative of an acute cannabinoid intoxication under varying DUI per se laws, despite having survived longer than the expected duration of cannabinoid impairment effects. This study examined decedents in whom quantified cannabis metabolites were detected in Connecticut medical examiner autopsy samples, in which the medically-confined survival interval was longer (4–12 and > 12 h) than the expected duration of cannabinoid impairment effects. Several of the 15 decedents, despite being intubated and/or comatose during the medically-confined period of abstinence, would have exceeded DUI per se limits based upon their toxicology results. The use of drug concentrations alone to equate to an acute cannabis intoxication may result in inappropriate arrest, prosecution, and civil liability.

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Correspondence to James R. Gill.

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Schwerdt, M.K., Gill, J.R. The pitfalls of per se thresholds in accurately identifying acute cannabis intoxication at autopsy. Forensic Sci Med Pathol 14, 497–502 (2018).

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  • Forensic pathology
  • Cannabinoids
  • Autopsy
  • Toxicology
  • Driving under the influence laws