Is credibility an art than a science?

[504] It is, of course, true that the assessment of the credibility of a witness is more of an “art than a science”. The task of assessing credibility can be particularly daunting where a judge must assess the credibility of two witnesses whose testimony is diametrically opposed. It has been held that “[t]he issue of credibility is one of fact and cannot be determined by following a set of rules.” See White v. The King, 1947 CanLII 1 (SCC), [1947] S.C.R. 268. It is the highly individualistic nature of a determination of credibility and its dependence on intangibles such as demeanour and the manner of testifying that leads to the well-established principle that appellate courts will generally defer to the trial judge’s factual findings, particularly those pertaining to credibility.

[505] Neither the parties nor the informed and reasonable observer should be led to believe by the comments of the judge that decisions are made based on generalizations. It is important that judges be aware of the social reality that support decisions based on an examination of the objectives of the legislation before him or her. One statement of the content and purpose of this doctrine is outlined in Varcoe v. Lee et al. (1919), 180 Cal. 338, 181 P. 223, at page 226: “The three requirements . . . — that the matter be one of common and general knowledge, that it be well established and authoritatively settled, be practically indisputable, and that this common, general, and certain knowledge exist in the particular jurisdiction — all are requirements dictated by the reason and purpose of the rule, which is to obviate the formal necessity for proof when the matter does not require proof.”