Once probative value is assessed and the risk of prejudice is identified in the context of the particular case, the final step is to balance the two, always bearing in mind that the similar fact evidence is prima facie
inadmissible, and that admission will be an exception that must be established as appropriate, on the balance of probabilities, by the Crown. As indicated, to prevent the prohibited inference there is merit in looking for probative value to exceed significantly the risk of prejudice that admission would present.122In R. v. Handy, Justice Binnie observed that a challenge in balancing probative value and prejudice is that there is no necessary inverse relationship between probative value and prejudice. When probative value increases, prejudice does not necessarily decrease.123Given that there is always a risk of prejudice when similar fact evidence is admitted, perhaps the best way to conduct the balancing exercise is to ask whether the similar fact evidence has been demonstrated to be sufficiently probative to justify running the risks of prejudice presented by the evidence.
This assessment is not scientific. The exercise is one of balancing competing considerations. Different judges can therefore come to different conclusions on the same facts without an error occurring.124Accordingly, the decision of the trial judge is entitled to "substantial deference," always bearing in mind that "[a] trial judge has no discretion to admit similar fact evidence whose prejudice outweighs its probative value,"125 and has no power to admit similar fact evidence that can do no more than raise the prohibited inference. An appeal court will interfere only if there has been a material error in principle in applying the law or where there is only one reasonable answer and the judge fails to arrive at it.126
 R. v. Pickton, above note 31 at para. 77.
 R. v. Handy, above note 10 at para. 149.
 R. v. Harvey, (2001), 48 C.R. (6th) 247 at para. 42 (Ont. C.A.), aff’d (2002), 7 C.R. (6th) 1 (S.C.C.).
 R. v. Handy, above note 10 at para...