What is the test for exclusion of evidence in a sexual assault case?

The test for exclusion is elaborated upon by D.M. Smith J. in Regina v. Webber [1999] B.C.J. No. 3218 (B.C.S.C.): ... Exclusion of the evidence will only occur where the probative value of such evidence is outweighed by the prejudicial effect to an accused that would render the trial process unfair. ... The determination of whether an accused's trial would be rendered unfair in circumstances where the admission of evidence would create a serious breach of ss. 7 and 11(d) of the Charter, requires the trial judge to weigh the probative value against the prejudicial effect of admitting such evidence. This weighing process requires a balancing of not only the accused's interests to a fair trial but also society's interests in having a determination of the accused's guilt or innocence. If the probative value of the evidence outweighs its prejudicial effect, then the evidence will be admitted and the quality of the evidence will go to its weight. If the probative value of the evidence is outweighed by its prejudicial effect on the accused's right to a fair trial, then the evidence will be excluded.

What is meant by a fair trial is addressed by McLachlin J. in Regina v. Harrer (1996) 1995 CanLII 70 (SCC), 101 C.C.C. (3d) 193 (S.C.C.) at para. 45: At base, a fair trial is a trial that appears fair, both from the perspective of the accused and the perspective of the community. A fair trial must not be confused with the most advantageous trial possible from the accused's point of view... Nor must it be conflated with the perfect trial; in the real world, perfection is seldom attained. A fair trial is one which satisfies the public interest in getting at the truth, while preserving basic procedural fairness to the accused.