Evidence - Opinion. R. v. Daou
In R. v. Daou (Ont CA, 2021) the Court of Appeal considered the admissibility of police opinion evidence about the credibility of another witness:
 In White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23,  2 S.C.R. 182, Cromwell J. said, at para. 14: “To the modern general rule that all relevant evidence is admissible there are many qualifications. One of them relates to opinion evidence, which is the subject of a complicated exclusionary rule.” That case concerned the parameters of expert opinion evidence, whereas this case is about the non-expert opinion evidence given by a police officer.
 Det. Monette was not qualified as an expert, nor could he have been. He had no special power, training, or ability to determine if someone is telling the truth. Moreover, had he been offered as an expert, his impartiality and lack of independence would surely have been fatal to being so qualified: see White Burgess, at paras. 46-53. Det. Monette’s opinion about the truthfulness of the appellant’s confession was inadmissible. It was for the jury to answer this question, without undue influence from a high-profile witness who had no business opining on the issue.
 Generally speaking, only properly qualified experts may provide opinion evidence, and only about matters of fact, not about legal issues. In Graat v. The Queen, 1982 CanLII 33 (SCC),  2 S.C.R. 819, the Supreme Court of Canada considered whether lay persons, in that case a police officer, could provide an opinion about whether a person’s ability to drive was impaired by the consumption of alcohol.
 In a searching analysis, Dickson J. (as he then was) concluded that, as a general rule, lay persons cannot give opinion evidence, but noted that the law recognized a number of exceptions, such as the identification of handwriting, a person’s apparent age, the emotional state of a person, and others: at p. 835. However, he drew a bright line between opining on matters of fact on the one hand, and legal standards on the other. Dickson J. said, at p. 839: “A non-expert witness cannot, of course, give opinion evidence on a legal issue as, for example, whether or not a person was negligent.” Similarly, an opinion that an accused person is guilty would be subject to the same prohibition.
 The Supreme Court addressed this issue in R. v. Van, 2009 SCC 22,  1 S.C.R. 716. In that case, the victim, Jack Kong, had been stabbed and robbed. He said his former friend Duc Van did it. At trial, Mr. Van claimed that someone else had attacked Mr. Kong. Mr. Van was convicted at trial. On appeal, this court set aside the convictions because one of the Crown’s key witnesses, a police officer, offered his opinion on Mr. Van’s guilt, and left the suggestion that his opinion was based partly on information that was not before the jury. He was also permitted to give evidence that fell into the category of investigative hearsay. Winkler C.J.O., in dissent on this point, would have dismissed the appeal by applying the curative proviso in s. 686(1)(b)(iii) of the Criminal Code: R. v. Van, 2008 ONCA 383, 92 O.R. (3d) 462, at para. 47, rev’d 2009 SCC 22,  1 S.C.R. 716.
 By a majority of 5:4, the Supreme Court overturned this court’s decision. All nine judges agreed that the disputed evidence was admissible, but only for a limited purpose. They also agreed that the jury should have been provided with a limiting instruction about the proper use of the investigative hearsay and police opinion evidence. The jury received no such instruction. The majority was prepared to apply the proviso; the minority was not.
 Although the main issue before the Supreme Court concerned the impact of the failure to provide a limiting instruction, both the majority and minority judgments are helpful on the question of the admissibility of the disputed evidence.
 For the majority, LeBel J. held, at para. 39, the evidence of the officer’s “statement of his opinion of the respondent’s guilt was unwarranted and clearly foreclosed by the jurisprudence, due to the danger of the jury uncritically accepting the witness’s opinion without drawing their own conclusions about the evidence (e.g. R. v. D.D., 2000 SCC 43,  2 S.C.R. 275, at para. 49)” (emphasis added).
 LeBel J. qualified his comments about admissibility. He agreed with this court that investigative hearsay and police opinion evidence were admissible as they pertained to the defence assertion of an inadequate police investigation: at para. 33, citing R. v. Dhillon (2002), 2002 CanLII 41540 (ON CA), 166 C.C.C. (3d) 262 (Ont. C.A.); R. v. Mallory, 2007 ONCA 46, 220 O.A.C. 239. See also Lisa Dufraimont, “Annotation to R. v. Van” (2009), 65 C.R. (6th) 195.
 In his reasons for the dissenting judges, Cromwell J., at para. 82, accepted the majority’s characterization of the opinion about Mr. Van’s guilt as clearly unwarranted and held that “[t]he opinions of the police on the question of an accused’s guilt have no place in the jury’s deliberations”: at para. 86. At para. 81, he cited the reasons of Major J. in D.D., where he said, at para. 49:
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. Cromwell J. elaborated on the dangers of the officer’s opinion evidence in the following paragraph, which contains obvious parallels to the circumstances of this case, at para. 82:
It is worth remembering that there are at least three dangers in receiving opinion evidence of the sort the officer gave in this case. First, it usurped the function of the jury by drawing critical inferences — a conclusion about the respondent’s guilt — from the facts known to the witness. Second, it obscured the factual basis for the conclusions reached. In this case, it was at best unclear and at worst a likely inference that the officer’s opinion was based on evidence other than that which had been admitted before the jury.[] Finally, there was a danger that, given the long experience and excellent career history of Det. Sgt. Nealon, the jury would attach undue weight to his opinion: see, for example, Graat v. The Queen, 1982 CanLII 33 (SCC),  2 S.C.R. 819, at pp. 839-40. All of the judges in Van agreed that, in the absence of an allegation of an inadequate investigation, the Crown is not permitted to adduce police opinion evidence (or investigative hearsay evidence). If such evidence is adduced, there must be a cautionary instruction that this type of evidence cannot be used to infer guilt.
 The admissibility of police opinion evidence has arisen in this court from time to time, sometimes in conjunction with demeanour evidence. For example, in R. v. Short, 2018 ONCA 1, 139 O.R. (3d) 1, the appellant was convicted of killing his wife. The defence took the position that the police had too quickly jumped to the conclusion that the appellant was responsible, to the exclusion of other suspects.
 In cross-examination, one of the police officers testified that, in his opinion, the appellant did not react to being questioned about the murder in the way that an innocent person would have reacted. Although the appeal was allowed on other grounds, the court addressed the obligations of the trial judge in these circumstances. Applying Van, Doherty J.A. held that the trial judge had to instruct the jury: (1) that the officer’s “opinion about the appellant’s veracity was irrelevant to their deliberations”; and (2) his “opinions about the appellant’s demeanour and the inferences that could be drawn from that demeanour could not be used by the jury as evidence of the appellant’s guilt”: at para. 58.
 Similarly, in R. v. Borel, 2021 ONCA 16, 153 O.R. (3d) 672, the accused was charged with attempted murder for setting the victim on fire. He gave a lengthy interview to the police in which he denied responsibility. At trial, the Crown adduced the evidence of the interviewing police officer. As in this case, the officer was very accomplished, with 27 years of experience, having worked in major crimes and homicide. As Nordheimer J.A. observed, at para. 30: “He made a point of telling the jury that he had interviewed approximately 500 accused persons during his 17 years as a criminal investigator.” Without objection, the officer gave evidence about the accused’s demeanour. He offered his opinion that his denials were “relatively weak” and that, based on his experience and training, “if someone’s in custody for an offence, a serious offence that they … did not commit, they would … likely be denying it strongly and asking why they’re in custody”.
 Nordheimer J.A. concluded that this opinion evidence was highly prejudicial. He relied on R. v. Quazi, 2014 ONCA 94, in which a police officer was permitted to give his opinion that the appellant’s demeanour during his police interview was indicative of guilt: at para. 36. In allowing the appeal in Quazi, this court held, at para. 7: “Such an opinion was irrelevant and should not have been permitted. Its intrusion into the trial record was highly prejudicial and contributed to the overall unfairness of the appellant’s trial.”
 In light of this line of authority, the opinion evidence offered by Det. Monette was inadmissible.