The accused, a pediatrician, was charged with sexually assaulting four teenage female patients.
At trial, the defence sought to introduce expert psychiatric evidence that the perpetrator of such offences would belong to a narrow class of individuals (e.g., pedophiles or sexual psychopaths) and that the accused did not possess the characteristics of this class.
The trial judge excluded the evidence, but the Court of Appeal ordered a new trial.
The Supreme Court of Canada allowed the Crown's appeal and restored the convictions, establishing a four-part test for the admission of expert evidence: relevance, necessity in assisting the trier of fact, the absence of any exclusionary rule, and a properly qualified expert.
The Court held the psychiatric evidence was inadmissible as it lacked sufficient reliability and necessity to overcome the exclusionary rule against character evidence.