Updating toxic psychosis into 21st-century Canadian: Bouchard-Lebrun v. R.

For centuries, Anglo-Saxon common law tradition has tended to limit voluntary intoxication as a defense on both mens rea (so-called diminished capacity defenses) and insanity. A new decision by the Supreme Court of Canada has clarified for Canadian jurisdictions whether voluntary substance-induced psychosis is a mental disorder for the purposes of determining insanity. In the United States, there is still considerable variation with regard to this question in such settled-insanity cases. This article is a review of Anglo-Saxon, American, and Canadian jurisprudence with regard to intoxication defenses on both mens rea and insanity. The factual and appellate history of Bouchard-Lebrun v. R. and a discussion of the Supreme Court's reasoning and the implications for future forensic practice follow. Potential pitfalls for forensic evaluators are explored, including the lack of scientific evidence available to detect individuals who, while appearing to present with a drug-induced psychosis, prove over time to have an endogenous psychotic illness.