Handle with care: Jury deliberation and demeanour-based assessments of witness credibility
| Author | James Chalmers,Fiona Leverick,Vanessa E. Munro |
| DOI | http://doi.org/10.1177/13657127221120955 |
| Published date | 01 October 2022 |
| Date | 01 October 2022 |
| Subject Matter | Articles |
Handle with care: Jury deliberation
and demeanour-based assessments
of witness credibility
James Chalmers
School of Law, University of Glasgow, Glasgow, UK
Fiona Leverick
School of Law, University of Glasgow, Glasgow, UK
Vanessa E. Munro
School of Law, University of Warwick, Coventry, UK
Abstract
It is unclear how effectively jurors perform their task of assessing witness credibility.
Drawing on evidence from a mock jury study involving 863 mock jurors deliberating across
64 juries, and building on existing research, this paper explores juries’reliance on demean-
our. While jurors make use of factors which the research literature suggests are often
appropriate credibility markers, for example external consistency of accounts, there is
cause for concern over the nuance with which jurors apply those assessments in high stakes
contexts. The manner in which jurors look to manner of delivery as evidence of credibility
is also problematic. The paper makes the case for a more circumspect approach towards
jurors’use of demeanour assessments. At a minimum, this requires that judicial directions
no longer advocate their reliability, but remind jurors of the complexities associated with
such assessments and the need to treat any conclusions grounded on presentational cues
with caution.
Keywords
demeanour, juries, jury directions, sexual offences, witness credibility
Corresponding author:
James Chalmers, School of Law, University of Glasgow, 5–8 The Square, Glasgow G12 8QQ, UK.
Email: james.chalmers@glasgow.ac.uk
Article
The International Journal of
Evidence & Proof
2022, Vol. 26(4) 381–406
© The Author(s) 2022
Article reuse guidelines:
sagepub.com/journals-permissions
DOI: 10.1177/13657127221120955
journals.sagepub.com/home/epj
Introduction
Within an adversarial criminal trial, one of the jury’s key roles is to assess witness credibility.
1
There will,
of course, be trials in which ‘what happened’is not in dispute and where the role of the jury lies primarily
in evaluative judgments about, for example, how much force is reasonable in self-defence. Most criminal
trials will, however, involve at least some element of competing factual testimony. It will be for the jury to
evaluate such accounts (and the witnesses providing them), with the aim of delivering an accurate verdict.
Nonetheless, it is unclear how –or how effectively –jurors perform this task. Restrictions on research
into the substance of jury deliberations in many jurisdictions mean we lack insight into the ways in which
jurors evaluate witness credibility in concrete cases, and the reliability and robustness of the factors
underpinning those assessments. Since, as a former Justice of the Supreme Court of British Columbia
put it, ‘in the courtroom, as in daily life, we are unequipped with the Lasso of Truth’(Smith, 2012:
13), jurors are likely to rely on a range of considerations and cues when assessing witness credibility.
Some of these will relate to the content of accounts, such as the extent to which claims made by one
witness are corroborated by other evidence. Others may relate to the delivery of those accounts, particu-
larly in cases where there is a lack of such additional evidence. Cues here might pertain to the demeanour
and presentation of the witness, including vocal cues (such as the tone and confidence with which their
testimony was given) or non-vocal cues (such as their body language or signs of emotional distress).
Indeed, in some jurisdictions, jurors are specifically directed by the judge to consider delivery cues in
their assessment of the evidence (or at least are not advised against drawing inferences from them). In
Scotland, for example, standard judicial directions advise jurors that in assessing credibility and reliabil-
ity they can ‘look at the content of witnesses’evidence, their body language in giving it, and compare
what they say with other evidence in the case’(Judicial Institute for Scotland, 2021: 5.13). In England
and Wales, the Crown Court Compendium suggests directing jurors that ‘it would be better not to
take so many notes that they are unable to observe the manner/demeanour of the witnesses as they
give their evidence’.
2
The importance of demeanour is similarly emphasised by judicial cautions to
the jury that where they hear evidence such as hearsay material, they should bear in mind the lack of
opportunity that has been afforded to them to assess demeanour,
3
and by case law holding that a
witness can be required to remove a niqab when testifying, given the importance of the jury seeing a wit-
ness’s face in evaluating their evidence.
4
What these directions do not do, however, is tell juries how they are to go about assessing demeanour.
The implication is that it is something to be left to the common sense of the jury, drawing on their ‘knowl-
edge of human nature’,
5
although in some jurisdictions it is recommended that the judge add the caveat
that giving evidence is a stressful experience and that ‘looks can be deceiving’.
6
In contrast to this
assumption that assessment of demeanour is a key –and typically relatively simple –part of the
1. Judges,of course, make these assessments too –in jurisdictions without juries and in jurisdictions that only use juries for the most
serious cases. Our primary interest here, however, is in the assessments that jurors make.
2. The Crown Court Compendium Part I: Jury and Trial Management and Summing Up (2020) page 3-5. See to similar effect page
3-33 on the situation where a jury is provided with a transcript of an ‘AchievingBest Evidence’interview: ‘it is what they see and
hear on the recording which is the evidence not what they read on the transcript. For this reason, they must take care to watch the
video as it is shown, so that they can assess the manner/demeanour of the witness when giving evidence.’
3. See e.g. The Crown Court Compendium Part I: Jury and Trial Management and Summing Up (2020) page 14-3 and Judicial
Institute for Scotland (2021: 32.3). It may be notable that in the recent case of Al Megrahi vHM Advocate 2021 SLT 73 at
[57]–[63], when discussing the caution required in assessing a statement not given on oath, Lord Justice-General Carloway
did not refer to the absence of an opportunity to assess demeanour.
4. RvNS 2021 SCC 72 (Canadian Supreme Court) (discussed in Snook et al. (2017)); RvD(R), Crown Court, 16 Sep 2013, unre-
ported (discussed in Nicolson (2014)).
5. Thomas vCommissioner of Police of the Metropolis [1997] QB 813 at 831.
6. A phrase found both in National Judicial Institute (Canada), Model Jury Instructions: 9.4 Assessment of Evidence (2018) [10] and
Judicial College of Victoria, Victorian Criminal Charge Book (2021) 1.11.
382 The International Journal of Evidence & Proof 26(4)
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