Using Artificial Intelligence for Demeanour Evidence

AuthorOmar Ha-Redeye
DateMarch 24, 2019

Demeanour evidence holds a controversial role in evidence law. Centuries of common law have allowed trial judges to assess the behaviour, conduct, and mannerisms to make findings of credibility. Often these findings can be useful to judges, especially when the only evidence available on crucial determinations of fact is viva voce testimony from each side.

In “Relying on Demeanour Evidence to Assess Credibility during Trial – A Critical Examination,” Amna Qureshi provides some background on the use of demeanour evidence,

The fact that trial judges can and do assess credibility based on demeanour during trial has also been held as an important reason for why appellate courts show considerable deference to the findings of a trial judge.

In R v Belnavis the Supreme Court stated that “the reasons for this principle of deference are apparent and compelling. Trial judges hear witnesses directly. They observe their demeanour on the witness stand and hear the tone of their responses. They therefore acquire a great deal of information which is not necessarily evident from a written transcript, no matter how complete.”
[citations omitted]

The inability to assess demeanour evidence was centrally important to determining the impact on trial fairness, including the ability of counsel to scrutinize and cross-examine the witness. In evaluating the allegations of sexual harassment by a lawyer, the Ontario Court of Appeal in Law Society of Upper Canada v. Neinstein reviewed the use of a Hearing Panel of demeanour evidence to conclude that the complainant gave evidence in a forthright and honest manner and withstood cross-examination well. The court ordered a new hearing, stating,

[66] …There is no insight provided as to why the Hearing Panel found [the Complainant] to be “forthright” and no indication of why it concluded she “withstood” cross- examination. Bald generalized assertions defy appellate review. Furthermore, while demeanour is a relevant factor in a credibility assessment, demeanour alone is a notoriously unreliable predictor of the accuracy of evidence given by a witness: see R. v. G. (G.), 1997 CanLII 1976 (ON CA), [1997] O.J. No. 1501, 115 C.C.C. (3d) 1 (C.A.), at pp. 6-8 C.C.C.; R. v. P-P. (S.H.), 2003 NSCA 53 (CanLII), [2003] N.S.J. No. 171, 176 C.C.C. (3d) 281 (C.A.), at paras. 28-30.

Demeanour evidence was most thoroughly evaluated in recent years in the Supreme Court of Canada case of R. v. N.S., where a sexual assault complainant wanted to testify while wearing her religious face covering (a”niqab”). The underlying decision in N.S. by the Ontario Court of Appeal highlighted some of the problems with demeanour evidence and its impact on trial fairness,

[55] Mr. Butt, counsel for N.S., makes the valid point that credibility assessments based on demeanour can be unreliable and flat-out wrong. Assessments of credibility based on demeanour can reflect cultural assumptions and biases. Judgments based on demeanour are no substitute for those based on a critical analysis of the substance of the entire evidence. Appellate courts have repeatedly cautioned against relying exclusively or even predominantly on demeanour to determine credibility. Mr. Butt also makes the valid point that the trier of fact does not lose all aspects of demeanour evidence if the witness wears a niqab. The trier of fact will still be able to consider the witness’s body language, her eyes, her tone of voice and the manner in which she responds to questions. All are important aspects of demeanour.

[56] It is, however, undeniable that the criminal justice system as it presently operates, and as it has operated for centuries, places considerable value on the ability of lawyers and the trier of fact to see the full face of the witness as the witness testifies. Appellate deference is justified to a significant extent on the accepted wisdom that trial judges and juries have an advantage over appeal judges in assessing factual questions because they, unlike appeal judges, have seen and heard the witnesses: R. v. M. (R.E.), 2008 SCC 51 (CanLII), [2008] 3 S.C.R. 3, [2008] S.C.J. No. 52, at p. 22 S.C.R. Similarly, the principled approach to the admission of hearsay evidence recognizes the value, insofar as the assessment of reliability is concerned, in the trier of fact’s ability to observe the witness’s demeanour as the witness made a statement which is proffered as evidence of its truth: see R. v. B. (K.G.), 1993 CanLII 116 (SCC), [1993] 1 S.C.R. 740, [1993] S.C.J. No. 22, at pp. 763-64 S.C.R.

[57] A witness’s appearance while testifying, in addition to assisting in assessing the witness’s credibility and providing non-verbal cues to assist the cross-examiner, may also further cross-examination in other ways in certain specific cases. There may be cases where the identity of the witness is an issue. In those cases, the opportunity to look at the witness may be essential to [page183] identifying the witness, which, in turn, may be crucial to effective cross-examination of that witness or to other aspects of the defence. For example, a witness may claim to have spoken to an accused at a certain time and place. Seeing the face of the witness may allow the accused to indentify the witness in a way that will assist the accused in the cross-examination and may perhaps also provide some explanation as to why the witness might fabricate or be mistaken about the content of the conversation.

The Supreme Court in this case affirmed the ability of trial judges to use demeanour evidence, but their conclusion was highly qualified based on the record before them,

[17] We have no expert evidence in this case on the importance of seeing a witness’s face to effective cross-examination and accurate assessment of a witness’s credibility. All we have are arguments and several legal and social science articles submitted by the parties as authorities.

[18] M—d S. and the Crown argue that the link is clear. Communication involves not only words, but facial cues. A facial gesture may reveal uncertainty or deception. The...

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