“Credibility is a primary vehicle for determining the truth of alleged facts. In the words of Justice Diamond, this task can be rendered “unenviably difficult” depending on the narrative put forward by the parties: Konstan v. Berkovits, 2023 ONSC 497, 2023 CarswellOnt 932 at para. 8.
In R. v. Gagnon, 2006 SCC 17, [2006] 1 S.C.R. 621 at para. 20, the Supreme Court of Canada cautioned that evaluating witness credibility is not “a science”.
Traditional criteria used to assess witness evidence includes witness demeanour, inherent probability in the circumstances, and internal and external consistency: Prodigy Graphics Group Inc. v. Fitz-Andrews, 2000 CarswellOnt 1178, 96 A.C.W.S. (3d) 177 at para. 46 per Justice Cameron.
Witness credibility is critical to the burden of proof: Konstan. Where a party has the burden to discharge a legal onus, I must satisfy myself, on a balance of probabilities, of “the credibility and reliability of the evidence in order to be in a position to make the relevant findings of fact”: Konstan, at para. 9.
Credibility differs from reliability. Credibility has to do with whether someone is honest, while reliability concerns whether their testimony is accurate: R. v. Sanichar, 2013 SCC 4, [2013] 1 S.C.R. 54 at para. 19. One may find a witness generally credible yet doubt their reliability. Conversely, a witness who is not credible may still offer reliable testimony.”