The Admissibility of Non-Expert Opinion Evidence
As a general rule, opinion evidence is not admissible; witnesses testify as to the facts which they perceived, not as to the inferences – that is, the opinions -- that they drew from their perceptions: Graat v. The Queen , 1982 CanLII 33 (SCC), [1982] 2 S.C.R. There is, however, an exception for witnesses duly qualified to express an expert’s opinion: R. v. Abbey, 1982 CanLII 25 (SCC), [1982] 2 S.C.R. 24. The opinion evidence of non ‑ expert witnesses is generally inadmissible. In R. v. D.D ., 2000 SCC 43 (CanLII), [2000] 2 S.C.R. 275at para. 49, Justice Major summarized this long-standing exclusionary rule: A basic tenet of our law is that the usual witness may not give opinion evidence, but testify only to facts within his knowledge, observation and experience. This is a commendable principle since it is the task of the fact finder, whether a jury or judge alone, to decide what secondary inferences are to be drawn from the facts proved. There is a...