What factors must be considered by the court in assessing the credibility of a witness?

Many factors must be considered by the court in an assessment of a witness’ credibility. As stated by Justice Adair in Gichuru v. Smith, 2013 BCSC 895 at paras. 129-130, aff’d 2014 BCCA 414:

The art of assessment of credibility involves examination of various factors such as: the witness’s ability and opportunity to observe events; the firmness of the witness’s memory; the witness’s ability to resist the influence of interest to modify his or her recollection; whether the witness's evidence harmonizes with independent evidence that has been accepted; whether the witness changes his or her testimony during direct and cross-examination; whether the witness's testimony seems unreasonable, impossible, or unlikely; whether a witness has a motive to lie; and the demeanour of a witness generally. See Bradshaw v. Stenner, 2010 BCSC 1398, at para. 186, aff’d 2012 BCCA 296.