Admissibility of Expert Opinion Evidence
In R. v. Abbey, 2009 ONCA 624 (CanLII), Doherty J.A. charted a two-step process for determining the admissibility of expert opinion evidence. Step One—the Mohan Criteria The four criteria from R. v. Mohan 1994 CanLII 80 (SCC), [1994] 2 S.C.R. 9 were absorbed under the first step: (i) Relevance, Relevance as a prerequisite to admission under this step , refers to logical relevance. Legal relevance is reserved for consideration under the second step, where the court performs its gatekeeper function: Abbey, at paras. 82-85. (ii) Necessity in assisting the trier of fact, Each case operates on its own facts. The assessment of necessity operates within the context of the facts In R. v. J.(J.L.), 2000 SCC 51 (CanLII), [2000] 2 S.C.R. 600, at para. 56, Binnie J. explained that the very purpose of expert evidence is to “assist the trier of fact by providing special knowledge that the ordina...