R. v. Graham, 2015 ONCA 113:
 Evidence as to an accused’s general disposition or bad character is presumptively inadmissible. This exclusionary rule seeks to guard against the risk of convicting an accused based not on proof related to the offence charged, but instead because he is a “bad person”. The rule seeks to prevent two kinds of prejudice to the accused: moral prejudice, in particular where the evidence is of previous misconduct that is more reprehensible than the offence charged and thus more likely to lead to a conviction based on an improper inference, and reasoning prejudice, which involves the potential distraction of the jury from its proper focus on the offence charged: R. v. Handy, 2002 SCC 56,  2 S.C.R. 908, at paras. 140, 144.
 However, the prohibition against admitting evidence of previous discreditable acts (or “similar fact evidence”) is not absolute. As Binnie J. remarked in Handy, at para. 41, “an issue may arise in the trial of the offence charged to which evidence of previous misconduct may be so highly relevant and cogent that its probative value in the search for truth outweighs any potential for misuse”. A trial judge may therefore admit similar fact evidence if she is satisfied on a balance of probabilities that in the context of the particular case the probative value of the evidence in relation to a particular issue outweighs its potential prejudice and thereby justifies its reception: Handy, at para. 55.
 Where similar fact evidence is introduced to prove identity, there are special considerations. A trial judge must first assess the degree of similarity between the acts in question to determine whether it is likely that the same person committed the alleged similar acts. Once it is determined on a balance of probabilities that the same person committed the alleged similar acts, the similar fact evidence may be admitted to prove that the accused committed the offence or offences in question: R. v. Arp,  3 S.C.R. 339, at para. 48.