Evidence - Discreditable Conduct. R. v. Houle
In R. v. Houle (Ont CA, 2022) the Court of Appeal comments on the use of discreditable conduct in evidence:
 In my view, the trial judge erred in law by excluding the prior incident evidence “because it does not disclose evidence of ‘prior discreditable conduct’”. The fact that prior conduct evidence is not discreditable is not a legally appropriate basis for exclusion. As Charron J.A. explained in R. v. B. (L.) (1997), 1997 CanLII 3187 (ON CA), 35 O.R. (3d) 35 (C.A.), at pp. 45-46, leave to appeal refused,  S.C.C.A. No. 524, the inquiry into whether prior conduct evidence is discreditable does not determine admissibility. Instead, it points the way to the admissibility rules that govern. If the prior conduct evidence is found to be discreditable and may thereby prejudice the accused, this will trigger the application of the similar fact evidence rule expressed in Handy, at p. 932. If, on the other hand, prior conduct evidence is not discreditable, the Handy rule will not have to be considered further, and the prior conduct evidence, if relevant, will be prima facie admissible.. R. v. J.W.
In R. v. J.W. (Ont CA, 2022) the Court of Appeal the court considers extensively the evidence law of 'discreditable conduct', apparently an uncertain form of similar evidence:
(1) The Governing Principles on the Admissibility of Discreditable Conduct Evidence
 This appeal requires this court to make another foray into what Dean Wigmore called, in 1940, “a vast morass of authority that was hopeless to reconcile” on the admissibility of discreditable conduct evidence. The morass is vaster today.
(a) Defining Discreditable Conduct Evidence
 Discreditable conduct evidence is evidence that:
(a) tends to show that the accused has committed an offence that is not the subject matter of the charge or charges before the court; or This definition is apt because the discreditable conduct in this case – public nudity – relates to a charge that was not the subject matter of the charges before the court and that a reasonable person would view with disapproval.
(b) tends to show behaviour on the part of the accused, either through prior or subsequent acts, records, statements or possessions,
(c) and which, in the opinion of the court, would be viewed with disapproval by a reasonable person.
(b) The Exclusionary Rule
 The rule is most simply expressed by McLachlin J. (as she then was):
[E]vidence which is adduced solely to show that the accused is the sort of person likely to have committed an offence is, as a rule, inadmissible. Whether the evidence in question constitutes an exception to this general rule depends on whether the probative value of the proposed evidence outweighs its prejudicial effect.In other words, there is a “general exclusionary rule” against the admission of evidence “going merely to disposition”. The Supreme Court repeated this language in Handy, which continues to be the seminal decision and governing precedent.
 The rule exists, said Binnie J. in Handy, because: “[t]he evidence, if believed, shows that an accused has discreditable tendencies,” so that the trier of fact might convict on that basis alone, with the prospect that “[i]n the end, the verdict may be based on prejudice rather than proof, thereby undermining the presumption of innocence”. This would be wrong: “[t]he forbidden chain of reasoning is to infer guilt from general disposition or propensity.”
 In order to overcome the presumption of inadmissibility, the Crown has to establish, on the balance of probabilities, that the probative value of the proposed evidence outweighs its prejudicial effect.
 An orderly methodology can be extracted from the cases and should guide trial judges in their assessment of the admissibility of discreditable conduct evidence.
(i) Defining the Issue
 The first step is to define with specificity the issue to which the evidence is asserted to be relevant because “[p]robative value cannot be assessed in the abstract”. Binnie J. noted in Handy that: “[t]he utility of the evidence lies precisely in its ability to advance or refute a live issue pending before the trier of fact”.
(ii) Identifying the Probative Value of the Discreditable Conduct
 The second step is to assess the probative value of the evidence. When evidence disclosing the accused’s discreditable conduct is offered, it is said to be probative because it exhibits similarity to the conduct underlying the charges faced by the accused. That is the way that the trial judge in this case approached the evidence of discreditable conduct, as will be discussed in more detail below. While the usual form of discreditable conduct evidence is “similar fact evidence” or “similar act evidence” as seen, for example in the cross-count application in this case, the principles laid out in Handy are applicable to discreditable conduct evidence beyond similar fact evidence.
 The assessment of probative value will vary from case to case. Identity cases are different from cases concerning motive, for example. The two critical elements are connectedness and similarity, as noted by Zarnett J.A. in R. v. Tsigirlash. There must be a:
logical “nexus established between the evidence of similar acts and the offence that the evidence is offered to prove”: MacCormack, at para. 49. Where the logical nexus depends on the similarity of the similar acts to the act charged, the probative value of the evidence will increase with the degree of similarity, because the probability that the similarity is a result of coincidence will decrease. The court must be satisfied that the “objective improbability of coincidence” has been established: R. v. Arp, 1998 CanLII 769 (SCC),  3 S.C.R. 339, at para. 48. This analysis cannot be done in the abstract, but only on the basis of specifically-identified similar acts. However, the Supreme Court has cautioned that:
The judge’s task is not to add up similarities and dissimilarities and then, like an accountant, derive a net balance. At microscopic levels of detail, dissimilarities can always be exaggerated and multiplied. This may result in distortion. At an excessively macroscopic level of generality, on the other hand, the drawing of similarities may be too facile. The similarities can be circumstantial. This court held in R. v. S.C., that “in sexual assault cases, similar circumstances are often more compelling than similarities or dissimilarities in conduct”. The circumstantial evidence showed that the accused had a “situation-specific propensity to seek out young females connected by family relationships”, which provided the evidence with sufficient probative value to be admitted. Watt J.A. stated in R. v. J.M.:
Where the evidence of similar acts is summoned in support of proof of the actus reus, it is not an invariable requirement that there be a strong peculiarity or unusual distinctiveness underlying the events being compared: Handy at para. 81. The cogency of evidence of similar acts may arise from the repetitive and predictable nature of an accused's conduct in closely defined circumstances.(iii) Identifying the Prejudicial Effects of the Discreditable Conduct
 The third step is to assess the prejudicial effect of the discreditable conduct evidence. Evidence showing the accused has committed an offence that is not the subject matter of the charge before the court can give rise to two forms of prejudice on the part of the trier of fact: “moral prejudice” and “reasoning prejudice”.
 On the one hand, “moral prejudice” identifies “the risk of convicting the accused because he is a ‘bad person’ rather than based on proof that he committed this offence” for which he is being tried. On the other hand, “reasoning prejudice” specifies the risk that a trier of fact will be distracted from a “proper focus on the charge itself aggravated by the consumption of time in dealing with allegations of multiple incidents…in divergent circumstances rather than the single offence charged”.
 Binnie J. stated in Handy that “distraction” as part of reasoning prejudice can take different forms. One form is emotional: the similar facts may raise “in the minds of the jury sentiments of revulsion and condemnation which might well deflect them from the rational, dispassionate analysis upon which the criminal process should rest”. (In my view a similar dynamic applies to a judge acting as a trier of fact.) Binnie J. noted that: “[t]he accused has a limited opportunity to respond” and is not “allowed to counter evidence of discreditable conduct with similar fact evidence in support of his or her credibility”. This can give rise to a trial fairness problem. Binnie J. observed that “the practical realities of the trial process reinforce the prejudice inherent in the poisonous nature of the propensity evidence itself”. 
 Another form of reasoning prejudice is when the trial focuses on the discreditable conduct itself, as a kind of trial within a trial, which can lengthen and complicate the trial, and distract the trier of fact from the issues on which liability turns.
 In light of the rule and the dangers that the admission of discreditable conduct evidence pose, trial judges should assess the prejudicial effect from three perspectives: moral prejudice, reasoning prejudice, and the presence of any factors that might reduce the impact of prejudice in the specific circumstances of the case.
 The first perspective of “moral prejudice” requires the trial judge in a judge-alone trial to self-instruct against the tendency to infer guilt based upon what Handy called the “forbidden chain of reasoning…from general disposition or propensity”. However, Paciocco et al. observe that “self-instruction by judges can reduce, but will not eliminate, the risk of moral prejudice.” They add that: “[s]ince the extent to which restricted admissibility doctrines can prevent moral prejudice is limited, courts must maintain a high awareness of the potential prejudicial effect of admitting similar fact evidence, particularly where the similar fact conduct is reprehensible”.
 There is less moral prejudice when the similar acts in question are other counts on the indictment, and therefore, more moral prejudice where the discreditable conduct is outside of the facts in the case: R. v. J.M., per Watt. J.A., at para. 87, and R. v. J.H., per van Rensburg J.A., at para. 24.
 The second perspective to be assessed is the reasoning prejudice posed in the specific circumstances of the case. This focuses both on the emotional form of reasoning provoked by the discreditable conduct, and also on the distraction from the facts in issue in the case that trying the issue of discreditable conduct might encourage.
 The third perspective is whether there are ways in which the possible prejudicial effects can be mitigated in the circumstances of the case. It has been said by this court that the risk of prejudice is “considerably reduced” in judge-alone trials. But Paciocco et al. note that: “there is controversy over how much lower the risk of prejudice is in judge-alone trials”. They add that: “[e]ven judges can struggle to overcome the tainting effect of discreditable information and may give it undue focus during a trial”. This observation is true to experience. Judges can by training and experience steel themselves against moral and reasoning prejudice, but only if they actively advert to the very point in the moment of decision.
 While the prospect that the accused might be able to testify in order to allay the prejudicial effects has been suggested to be a mitigating factor, this is doubtful, given what Binnie J. described in Handy as the “poisonous nature” of the evidence. Further, admitting the discreditable conduct evidence might effectively force the accused to testify in a case where doing so might be inadvisable for other reasons.
(iv) Weighing Probative Value Against Prejudicial Effect
 The fourth step in the methodology is to weigh the probative value of the discreditable conduct evidence against its prejudicial effects. Although this step is sometimes called a “balancing”, that is not an apt metaphor because, as Binnie J. noted in Handy: “[t]he two variables do not operate on the same plane”. The two are actually incommensurable. Nonetheless, as Binnie J. observed, even though “probative value and prejudice pull in opposite directions” in addressing the admissibility issue, “their conflicting demands must be resolved”. Generally, the more highly probative the evidence, the more likely it is that the interests of justice will require it to be admitted because of society’s interests in getting to the truth of the charges. However, the interests of both society and the accused in a fair trial process require that the dangers of propensity evidence be taken extremely seriously; the criminal justice system “should not (and does not) take lightly the dangers of misapplied propensity evidence”.