The Supreme Court of Canada has said that, notwithstanding the absence of corroboration in a case involving historic abuse, a finding of credibility is still possible: http://scc-csc.lexum.com/scc-csc/scc-csc/en/item/6211/index.do
In that case, the plaintiff FH had been a resident from 1966 to 1974 of the Sechelt Indian Residential School, an institution operated by the Oblates of Mary Immaculate. Though FH claimed to have been sexually assaulted by M, an Oblate Brother, when he was 10, he told no-one about it until 2000, when he confided in his wife.
Despite inconsistencies in his testimony as to the frequency and gravity of the sexual assaults, the trial judge found him to be credible, concluding that he had been anally raped by M on four occasions during the 1968‑69 school year….
A majority of the Court of Appeal overturned that decision on the grounds that the trial judge had failed to consider the serious inconsistencies in FH’s testimony in determining whether the alleged sexual assaults had been proven to the standard of proof that was “commensurate with the allegation….”
In allowing the appeal, the Supreme Court of Canada said, among other things, that, in serious cases such as this one—where there is little other evidence than that of the plaintiff and the defendant, and the alleged events took place long ago—the judge is required to make a decision.
Sexual assault victims need not provide independent corroborating evidence. Such evidence may not be available, especially where the alleged incidents took place decades earlier. Also, incidents of sexual assault normally occur in private. Hence, trial judges may be required to make a decision on the basis of whether they believe the plaintiff or the defendant. As difficult as that may be, they must assess the evidence and make their determination without imposing a legal requirement for corroboration.