On February 1, 2007, Canada became the first country to impose a blanket prohibition on witness testimony obtained under hypnosis. In a 6-3 decision in R. v. Trochym, the Supreme Court ruled that such testimony is too unreliable to be admitted.
“This technique and its impact on human memory are not understood well enough to be sufficiently reliable to be used in a court of law,” wrote Justice Deschamps for the majority. “Although hypnosis has been the subject of numerous studies, these studies are either inconclusive or draw attention to the fact that hypnosis can, in certain circumstances, result in the distortion of memory.”
Writing for the minority, Justice Bastarache argued against a blanket prohibition, stating that hypnosis was an established science and that “the admissibility of such evidence should always be made on a case-by-case basis.”