What is the burden of corroboration in determining a claim of sexual assault?

The leading articulation of this burden was set out in Koop v. Smith (1915), 1915 CanLII 26 (SCC), 51 S.C.R. 554, where Duff J. held: I think the true rule is that suspicious circumstances coupled with [a close] relationship make a case of res ipsa loquitor which the tribunal of fact may and will generally treat as a sufficient prima facie case, but that it is not strictly in law bound to do so; and that the question of the necessity of corroboration is strictly a question of fact.