“…one of the most valuable means of assessing witness credibility is to examine the consistency between what the witness said in the witness box and what she has said on other occasions, whether or not under oath: R. v. G. (M.) (1994), 1994 CanLII 8733 (ON CA), 93 C.C.C. (3d) 347 (Ont. C.A.), at p. 354, leave to appeal to S.C.C. refused, [1994] S.C.C.A. No. 390. Inconsistencies may emerge in a witness’ testimony at trial, or between their trial testimony and statements previously given. Inconsistencies may also emerge from things said differently at different times, or from omitting to refer to certain events at one time while referring to them on other occasions.
Inconsistencies vary in their nature and importance. Some are minor, others are not. Some concern material issues, others peripheral subjects. Where an inconsistency involves something material about which an honest witness is unlikely to be mistaken, the inconsistency may demonstrate a carelessness with the truth about which the trier of fact should be concerned: G. (M.), at p. 354.”