As stated by the Supreme Court of Canada, "[i]t is trite law that ‘character evidence [called by the Crown] which shows only that the accused is the type of person likely to have committed the offence in question is inadmissible.’"7Moreover, even where it logically follows it is impermissible to infer from admissible evidence that the accused may be guilty because he is the kind of person who would commit the offence. This "prohibited inference" has been described as a "primary rule of exclusion,"8"one of the most deeply rooted and jealously guarded principles of our criminal law."9Hence, it is not permissible in a burglary trial to prove that, because he has a history of burglary, the accused is the kind of person likely to have committed the burglary in question.
Justice Binnie explained why the prohibited inference exists in the unanimous Supreme Court of Canada decision in R. v. Handy, now the leading Canadian case on character evidence:
Proof of general disposition is a prohibited purpose. Bad character is not an offence known to law. Discreditable disposition or character evidence at large, creates nothing but "moral prejudice" and the Crown is not entitled to ease its burden by stigmatizing the accused as a bad person.10This is not to say that general disposition or general character is entirely without relevance. Surely it is easier to believe an allegation that the accused committed a burglary, knowing that, because he has committed burglaries before, he is the kind of person who would do so. Yet the relevance of this general character evidence is modest when it comes
to resolving whether the accused committed the particular burglary alleged. More importantly, relying on inferences arising from general disposition or general character is dangerous. It is apt to add more heat than light.11It may cause the trier of fact to convict, not because of the natural strength of the kind of evidence, but as a reaction to the discreditable, contemptible, or stigmatizing character of the accused. For these reasons, in spite of its modest relevance, evidence that does no more than invite the prohibited inference is inadmissible.
Even though the existence of the prohibited inference is "not controversial,"12its precise contours have been the source of confusion. Until Handy, it was common for judges and legal commentators to use the misleading short form of "propensity reasoning" to describe the prohibited inference. They said...