What is the legal test for a summary conviction?

Hearing summary conviction appeals, I am permitted to review the evidence to determine whether the trial judge could reasonably have reached the conclusion he did on the evidence before him. I am not permitted to retry the case. I am permitted to re-examine and, to some extent, re-weigh and consider the effect of the evidence to determine if it provided an evidentiary basis upon which the trial judge could reasonably reach the decision he did. Burke v. The Queen (1996), 1996 CanLII 229 (SCC), 105 C.C.C. (3d) 205 (S.C.C.).

An appellate court ought not to substitute its own views for that of the trial judge once it finds a reasonable evidentiary foundation existed. With respect to findings of credibility, an appellate court is not permitted to substitute its own conclusion in regards to a witness that the court has neither seen nor heard. Where a conviction turns on the question of credibility, an appellate court may only overturn the conviction if it is satisfied that the basis for finding of credibility is so tenuous, fraught with difficulties or the evidence incredible to the extent that the trial judge’s credibility assessment cannot be said to have been supported by the evidence. Francois v. The Queen (1994), 1994 CanLII 52 (SCC), 91 C.C.C. (3d) 289 (S.C.C.).