A 37-year-old, one-pack-per-day tobacco smoker collapsed and died at home. At autopsy, he had an occluded left anterior descending coronary artery. Δ(9)-Tetrahydrocannabinol-carboxylic acid was found in his urine but no cannabinoids were detected in his blood. Misadventure was the inquest verdict on the basis of the urinary cannabis, with acute myocardial infarction as the primary cause and cannabis as the secondary cause of death. Such a conclusion is a misinterpretation of the evidence when the time duration for cannabis as a trigger for myocardial infarction is at most two hours. The absence of cannabis in the blood likely places the time since inhalation at more than two hours. The role of tobacco smoking as a trigger was ignored. Cotinine, the biochemical marker of tobacco smoke, should be added to the standard toxicological screen in the guidelines on autopsy practice of the Royal College of Pathologists.