When is the W.D. instruction required?
A W.D-type instruction simply applies the burden of proof to any exculpatory account advanced by the defence. See R. v. D. (W). (1991), 1991 CanLII 93 (SCC). The principles underlying W.(D.) are not confined merely to cases where an accused testifies and his or her evidence conflicts with that of Crown witnesses. They have a broader sweep. Where, on a vital issue, there are credibility findings to be made between conflicting evidence called by the defence or arising out of evidence favourable to the defence in the Crown’s case, the trial judge must relate the concept of reasonable doubt to those credibility findings. The trial judge must do so in a way that makes it clear to the jurors that it is not necessary for them to believe the defence evidence on that vital issue; rather, it is sufficient if – viewed in the context of all of the evidence – the conflicting evidence leaves them in a state of reasonable doubt as to the accused’s guilt. In that event, ...