If a misapprehension played an essential part in the trial judge’s reasoning process leading to the conviction, the conviction is not saved even if the evidence at trial was capable of supporting a conviction

R. v. Gough, 2013 ONCA 137 is a useful source for the principle that a factual misapprehension can be fatal if it goes to an essential part of the Court’s reasoning:

[24]       The question that follows is the extent to which, if at all, this misapprehension affected the trial judge’s reasoning process, resulting in his conclusion that the appellant is the robber. If the misapprehension played an essential part in the trial judge’s reasoning process leading to the conviction, the conviction is not saved even if the evidence at trial was capable of supporting a conviction: R. v. Lohrer (2004), 2004 SCC 80, 193 C.C.C. (3d) 1 (S.C.C.), citing R. v. Morrissey (1995), 22 O.R. (3d) 514,97 C.C.C. (3d) 193 (Ont. C.A.), at para. 93.