What is the effect of failing to call a material witness?

An unfavourable inference can be drawn when, in the absence of an explanation, a party fails to adduce the evidence of a witness who would have knowledge of the facts and who would be assumed to be willing to assist that party. In the same vein, an adverse inference may be drawn against a party who does not call a material witness over whom he or she has exclusive control and does not explain it away. Such failure is said to amount to an implied admission that the evidence of the absent witness would be contrary to the party's case, or at least would not support it (see Murray v. City of Saskatoon (1952), 1951 CanLII 202 (SK CA), 2 D.L.R. 499 at 505-6).