What is the test for admitting evidence of prior sexual assaults?

The trial judge ruled that the evidence of the alleged prior sexual assaults was not admissible under what is commonly referred to as the similar fact rule of evidence. He relied on the decision of Guay v. R., 1978 CanLII 148 (SCC), [1979] 1 S.C.R. 18, 6 C.R. (3d) 130, 42 C.C.C. (2d) 536, 89 D.L.R. (3d) 532, 23 N.R. 451 [Que.], and in particular, the statement of Pigeon J. at p. 547 that the admissibility of such evidence is "essentially in the discretion of the trial Judge", a discretion to be exercised in accordance with the "general principles established by the cases". The trial judge quoted Pigeon J.'s statement that it is well established that such evidence may be admitted to rebut a defence of innocent association and alluded to the fact that similar fact evidence may be admissible to establish sexual passion.