What is the test for an appellate court to overturn a finding of not guilty of sexual assault?

Because of the factual basis and discretionary nature of these decisions, they are accorded significant deference on review. Absent a material error of fact or law (i.e., the trial judge failed to consider relevant evidence or factors) or an omission that “gives rise to the reasoned belief that the trial judge must have forgotten, ignored or misconceived the evidence in a way that affected his conclusion”, an appellate court cannot reconsider the evidence and arrive at a different decision from that of the trial judge: Van de Perre v. Edwards, 2001 SCC 60, [2001] 2 S.C.R. 1014 at para. 15.