Stop Assessing Credibility Outside of the Box: Why Adjudicators Should Only Consider Demeanour of a Witness While on the Witness Stand

Assessing credibility is a critical role for adjudicators, in many cases. How to assess credibility requires its own book, but in this column, I will focus on the inappropriateness of relying on the facial and physical reactions (otherwise known as demeanour) of a party when they are not on the witness stand.

The relevance of demeanour is a persistent myth in adjudication. Even though studies have shown that our ability to judge whether someone is lying solely by their demeanour is about 50% (no better than a coin toss), it still is considered by the courts to be a factor to consider in assessing credibility (see, for example, R. v. N.S., 2012 SCC 72). While being careful not to disagree with the Supreme Court, other courts have significantly downplayed the value of demeanour, as succinctly stated by the Ontario Court of Appeal in R. v. Rhayel, 2015 ONCA 377:

[85] Cases in which demeanour evidence has been relied upon reflect a growing understanding of the fallibility of evaluating credibility based on the demeanour of witnesses … It is now acknowledged that demeanour is of limited value because it can be affected by many factors including the culture of the witness, stereotypical attitudes, and the artificiality of and pressures associated with a courtroom. One of the dangers is that sincerity can be and often is misinterpreted as indicating truthfulness.

But what of the demeanour of a witness when they are observing other witnesses – in other words, when they are at the front of the hearing room? In R. v. T.M., 2014 ONCA 854, the Ontario Court of Appeal dealt with an appeal of a sexual assault conviction where the trial judge had relied upon the accused’s demeanour while listening to the testimony of other witnesses. When the accused did testify, the judge did not ask him for an explanation of his demeanour. Justice Laskin stated that the reliance of “out-of-box” demeanour comes with a higher risk of an accused being treated unfairly and a judge misinterpreting what was observed:

… most witnesses expect to be judged on their demeanour while testifying as well as on the substance of their evidence. They recognize that people communicate both verbally and non-verbally and that the two cannot always be separated. I do not think witnesses have the same expectation when they are not in the witness box.

[A] related concern … is the potential unfairness of the trial judge’s reliance on the accused’s demeanour outside the witness box when the trial judge does not give the accused any opportunity to explain the accused’s courtroom demeanour.

A recent decision of the Nova Scotia Court of Appeal (R. v. D.C., 2023 NSCA 20) illustrates the problem with relying on observations of a witness when not under oath or affirmation. In a sexual assault trial, the trial judge noted the behaviour of the accused while the complainant was testifying: “…the accused did not look at her, but instead stared off into the corner of the courtroom… It seemed to be a very purposeful act”. The trial judge continued, “…the studious ignoring of the complainant by the accused was something I had never seen before in close to 40 years being in court on a regular basis. …”. The trial judge relied on this observation as one aspect of his assessment of credibility.

The Court of Appeal held that it was clear from the trial judge’s words that the accused’s behaviour in the courtroom made a negative impression on him and it had an impact on the assessment of his credibility. The Court stated that the behaviour of a witness outside of the witness box is not usually relevant because that conduct is not evidence. The Court also referred to serious trial fairness concerns of relying on such conduct:

…It is a foundational principle that an accused is entitled to know the case against them, and to be able to respond accordingly. An accused has the ability to respond to evidence introduced during trial by choosing to call evidence, by discussing evidence in their submissions, or both. The same cannot be said of a judge’s observations of behaviour outside of the witness box which are only disclosed at the time of conviction.

The Court did note that there may be some circumstances where relying on these observations would not result in the setting aside of a conviction. However, that will only be the case where the trial judge gave other cogent and detailed reasons for the credibility assessment. In the circumstances of this case, basing a credibility assessment, even in part, on factors the accused had no ability to respond to, was an error of law and the appeal against the conviction was allowed.

From these criminal law cases, I think we can take the following lessons to apply to the tribunal hearing setting:

  • Reliance on demeanour when a witness is not testifying is unreliable
  • If the conduct of a witness outside of the witness box is significant and the adjudicator believes that conduct will be a factor in assessing credibility, the witness must be given an opportunity to provide an explanation

There is a recognition by lawyers that behaviour in the hearing room – outside of the witness box – may have an impact on a decision-maker’s assessment of credibility. In a recent book by Justice Cameron Gunn, Mona Duckett and Patrick McGuinty (Witness Preparation, Presentation and Assessment) the following instruction to witnesses from counsel is suggested: “You are being judged so be careful how you act before, during, and after your testimony”.

Adjudicators must be careful not to let perceptions of the demeanour of a witness when not testifying to influence findings on credibility – consciously or unconsciously. In other words, thinking “outside of the box” is to be discouraged, when assessing credibility.


  1. Has nobody ever watched CSI? The evidence tells the truth… not people. Black Robe Anxiety can change how a person behaves. Their true oral evidence may seem to be not credible as a result.
    Regardless, there is a difference between credibility and reliability and that’s where the evidence comes in. A witness may be perfectly credible but totally wrong in their recollection.. or a persuasive liar. If the crefible witness gives evidence that conflicts with the evidence…. it is likely unreliable. Therefore an Adjudicator must assess both credibility and reliability.
    Gerald Genge, Adjudicator

  2. Alastair Clarke

    Interesting points. When your article caught my eye, I was thinking it related to immigration law. I suppose our practices are so siloed these days that I expect everything to be within my regular feed. Nice to get the perspective of criminal law. At our recent CBA National Immigration conference, senior lawyer (and mentor) Barb Jackman urged us to look at caselaw outside immigration and to include citations from other areas of practice in our memos to the Court.

    Credibility is, of course, a huge area within immigration and there are reams of cases that relate to how Adjudicators assess the credibility of witnesses and documents. (Although, I suppose I should not write “of course” and I should not assume all readers are familiar with immigration practices.) The IRB provides a detailed guide to a proper credibility assessment here:

    It is rare that a matter at the RPD lacks a clear credibility determination as that would likely be a reviewable error. (Yes, I have done many appeals that include that basis.) When I am preparing clients and/or witnesses to give testimony, I often think to myself that my job is done if they get a positive credibility determination. Their matter may be refused for many other reasons, of course, but if they are accepted as credible, the work & preparation on my side was not in vain.

  3. I always learn from Slaw and today it’s helping patch up my weak command of evidence law. To that end I have a couple of questions. If demeanour is not a reliable indicator of credibility, why should it be relied upon at all? Why is it more legitimate to rely on demeanour when the person is in the witness box rather than outside of it?

    I’m also curious about people being given opportunities to explain their demeanour. Is this something that typically happens when a the finder-of-fact is inclined to make a credibility finding regarding in-the-box demeanour? Is it common for a judge/adjudicator, or counsel for the witness, to ask him or her why they had a certain facial or physical reaction?

  4. @Gerald Genge:

    How do we know what the “evidence” is, except through people?

    Yours Sincerely

Leave a Reply

(Your email address will not be published or distributed)