"[P]otential prejudice to the accused may be assessed in the following manner:
· by considering the potential for ‘moral prejudice’ against the accused. ‘Moral prejudice’ means the risk of convicting the accused because he is a ‘bad person’ rather than based on proof that he committed the offence; and
· by considering the potential for ‘reasoning prejudice’ against the accused, meaning the risk of distracting or confusing the jury, or of undue consumption of time, and the danger that the jury may have difficulty disentangling the subject matter of the charges from the similar fact evidence." 106
Moral prejudice refers to the risk that the evidence will be used to infer guilt based on the "forbidden chain of reasoning . . . from general disposition or propensity."107Of interest, Justice Binnie noted that model jury behaviour studies call into question the effectiveness that a judge’s limiting instruction not to use the forbidden chain of reasoning will have. In R. v. Last Justice Deschamps cautioned that jury directions do not remove but only reduce the risk of moral prejudice.108The limits on what restricted admissibility doctrines can achieve reinforce the need to maintain a high awareness of the potential prejudicial effect of admitting similar fact evidence, particularly where the similar fact conduct is reprehensible.
The Supreme Court of Canada cautioned in Shearing that where the similar fact evidence reveals a "morally repugnant act" its potentially poisonous nature will require a correspondingly high probative value to overcome its impact.109In Shearing itself the evidence was deeply disturbing, revealing a pattern of the misuse of religious authority to sexually exploit adolescents. It took highly probative evidence to justify running the risks of moral prejudice this proof would cause.
Similar fact evidence will also raise a real risk of moral prejudice where, as in R. v. Handy, the similar fact incidents are more reprehensible than the charge before the court.110By contrast, where the offence charged is significantly more troubling than the similar fact evidence, the risk of moral prejudice is diminished. In R. v. Talbot proof that the accused plied young boys with alcohol without sexually assaulting them caused only a modest risk of prejudice where he was charged with intoxicating and then sexually assaulting other boys.111
The risk of moral prejudice is considered to be modest where the similar fact evidence involves prior acts of aggression against the victim of the crime charged. This is because of the theory that the evidence of prior threats or abuse of the victim is so closely connected to the specific charge that it is unlikely a...