Although most eyewitnesses are not dishonest, they may nevertheless be grossly mistaken in their identification:
Since perception and memory are selective processes, viewers are inclined to fill in perceived events with other details, a process which enables them to create a logical sequence. The details people add to their actual perception of an event are largely governed by past experience and personal expectations. Thus the final recreation of the event in the observer’s mind may be quite different from reality.
Law Reform Commission of Canada Study Paper on Pretrial Eyewitness Identification Procedures (1983), at p. 10, quoted in R. v. Miaponoose (1996), 110 C.C.C. (3d) 445 (Ont. C.A.), at p. 422.
Eyewitness identification is inherently unreliable. It is difficult to assess, is often deceptively reliable because it comes from credible and convincing witnesses, and is difficult to discredit on cross-examination for those same reasons.
Certainty should not be mistaken for accuracy.
See, for instance, R. v. M.B., 2017 ONCA 653, at para. 61.
Studies have shown that triers of fact place undue reliance on such testimony when compared to other types of evidence. As a result, many wrongful convictions result from faulty, albeit convincing, eyewitness testimony, even in cases where multiple witnesses identify the same person.
See R. v. Miaponoose (1996), 110 C.C.C. (3d) 445 (Ont. C.A.), at pp. 450-451, and R. v. A. (F.) (2004), 183 C.C.C. (3d) 518 (Ont. C.A.), at para. 39.
For these reasons, although identification is a matter of fact, appellate courts will subject such findings to closer scrutiny than other findings of fact. Justice Doherty has summarized this approach in the context of an unreasonable verdict argument:
While recognizing the limited review permitted under s. 686(1)(a)(i), convictions based on eyewitness identification evidence are particularly well suited to review under that section. This is so because of the well-recognized potential for injustice in such cases and the suitability of the appellate review process to cases which turn primarily on the reliability of eyewitness evidence and not the credibility of the eyewitness.
R. v. Tat (1997), 117 C.C.C. (3d) 481 (Ont. C.A.), at paras. 99-100.
Eyewitness testimony is in effect opinion evidence, the basis of which is very difficult to assess. The witness’ opinion when she says ‘that is the man’ is partly based on a host of psychological and physiological factors, many of which are not well understood by jurists.
Miaponoose, at p. 422.
Identification Based on a Video Recording
Witness identification based on video recordings can under certain circumstances be more reliable as it allows repeated and unhurried consideration.
R. v. Nikolovski,  3 S.C.R. 1197, at para. 23, for instance, contemplates a videotape of “sufficient clarity and quality” that it would be reasonable for the trier of fact to use it as the sole basis for identifying the accused.
The trier of fact must use greater caution where the video or photo quality is poor.
R. v. Cuming (2001), 158 C.C.C. (3d) 433 (Ont. C.A.), at para. 19.
R. v. M.B., 2017 ONCA 653.