Simon's Megalomaniacal Legal Resources

Evidence - Expert - Standard of Review (SOR)

. R. v. Mohamed

In R. v. Mohamed (Ont CA, 2025) the Ontario Court of Appeal allowed criminal appeals, here from convictions for first-degree murder for three defendants regarding the same victim.

Here the court considers the appellate SOR for expert opinion issues:

[141] Absent an error in principle, a material misapprehension of evidence, or an unreasonable conclusion, deference is owed to a trial judge’s decision to admit expert opinion evidence: R. v. Mills, 2019 ONCA 940, 151 OR (3d) 138, at para. 47, leave to appeal refused, [2021] S.C.C.A. No. 263 (Mills), and [2021] S.C.C.A. No. 264 (Williams); R. v. Oppong, 2021 ONCA 352, 156 OR (3d) 401, at para. 34, leave to appeal refused, [2021] S.C.C.A. No. 255.

. 2089322 Ontario Corporation v. Des Roches

In 2089322 Ontario Corporation v. Des Roches (Ont CA, 2025) the Ontario Court of Appeal dismissed an appeal, here from "two orders dealing with the enforceability of a joint venture agreement ... providing for the establishment and operation of a convenience store and gas bar (the “Rezmart Business”) on the lands of the Wasauksing First Nation (the “WFN”)."

Here the court considers the deference accorded to a trial judge's assessment of expert evidence:

[38] The application judge did not commit any of these alleged errors. It is well established that the weight to be given an expert’s opinion is within the discretion of the trier of fact and deference is owed on appeal: R. v. S.A B., 2003 SCC 60, 14 CR (6th) 205, at paras. 62-63. It is not open to a reviewing court to carry out its own assessment of the probative value of an expert’s testimony or opinions simply because it may disagree with the assessment reached in the court below. Nor should a reviewing court interfere with a trial judge’s preference for one expert opinion over another unless the choice is unreasonable or patently wrong: Mouvement Laïque Québécois v Saguenay (City), 2015 SCC 16, [2015] 2 S.C.R. 3, at para. 105; Petz v Duguay, 2018 ABCA 402, at para. 10, leave to appeal to S.C.C. refused, 38495 (June 13, 2019).