Character Evidence. R v Bos
In R. v. Bos (Ont CA, 2016) the Court of Appeal sets out the basic approach of the court to the admission of character evidence, here referred to in it's negative form as 'discreditable conduct' evidence:
 Evidence is discreditable when it tends to show conduct of the accused, which would be viewed with disapproval by a reasonable person, beyond what is alleged in the indictment: see e.g. R. v. Johnson, 2010 ONCA 646 (CanLII), at para. 90.
 Such evidence is presumptively inadmissible because “[i]ts potential for prejudice, distraction and time consumption is very great and these disadvantages will almost always outweigh its probative value”: R. v. Handy, 2002 SCC 56 (CanLII),  2 S.C.R. 908, at para. 37.
 In Johnson, at paras. 97-101, Rouleau J.A. discussed the jurisprudence on discreditable conduct evidence adduced to support motive. He explained that such motive evidence is not automatically admissible. Rather, the trial judge must satisfy herself or himself that the probative value of the evidence outweighs its prejudicial effect. He noted that discreditable conduct evidence that is adduced to advance a speculative theory of motive ought to be excluded. However, “evidence that provides the trier of fact with real insight into the background and relationship between the accused and the victim, and which genuinely helps to establish a bona fide theory of motive is highly probative”, and thus more likely to outweigh its inherent prejudicial effect: Johnson, at para. 101.