Near the beginning of many judgments after a trial there is a section where the judge gives their view of the reliability and credibility of the witnesses. In about 98% of cases it is not necessary to read further to find out who the winner is going to be. The judge’s assessment of the witnesses is usually the key factor in the case. Penny Cooper is an expert in the effective participation of vulnerable witnesses and parties. Here she sets out the academic research on this issue.


Psychological Research and Witness Evidence in the Civil Courts of England & Wales

Witness lying and deceit 
Spotting signs that a witness is lying is a challenge for trial lawyers and fact-finders. Lawyers do not always see eye to eye (no pun intended) on the value of non-verbal ‘cues’, and neither do academics.
In R. v N.S. 2012 SCC 72 the Supreme Court of Canada (SCC) ruled that permitting the witness to wear the niqab while testifying could create a serious risk to trial fairness. Snook, McCardle, Fahmy and House, responded with a 2017 article, Assessing Truthfulness on the Witness Stand: Eradicating Deeply Rooted Pseudoscientific Beliefs about Credibility Assessment by Triers of Fact. The authors reviewed psychological research on detecting deception and concluded,
…most cues to deception are too faint for reliable detection, most facial expressions and other non-verbal cues are unrelated to deception, legal professionals (and others) are unable to accurately detect deception beyond chance levels, and that training people to use non-verbal cues to improve their deception detection is unviable.
Snook et al. believe that the SCC’s conclusions are ‘diminished significantly’ by the research evidence because the use of non-verbal communication for witness credibility assessment is largely unsupported by scientific research.  However, Denault and Jupe (2018) responded with Detecting Deceit During Trials: Limits in the Implementation of Lie Detection Research — A Comment on Snook, McCardle, Fahmy and House. They contend that Snook et al. (i) did not consider the distinctive characteristics of a trial and (ii)  did not consider additional research on non-verbal communication and deception detection. Denault and Jupe conclude that psychological research shows that fact finders should not underestimate the value of a witness’s non-verbal communication. (If you would like to request a copy of Denault and Jupe’s 2018 publication, please contact Louise Jupe directly at louise.jupe@port.ac.uk.)
Witness memory
Psychological research on witness memory is another area which has recently received significant attention, this time from judges in England and Wales. In Gestmin SGPS SA v Credit Suisse (UK) Ltd [2013] EWHC 3560 (Comm) Leggatt J (as he then was, now Leggatt LJ) made this observation (paragraph 16) which has gone on to strike a chord with many:
While everyone knows that memory is fallible, I do not believe that the legal system has sufficiently absorbed the lessons of a century of psychological research into the nature of memory and the unreliability of eyewitness testimony.
Leggatt J’s judgment in Gestmin has caught the attention of at least one Justice of the United Kingdom Supreme Court; in R (on the application of Bancoult No 3) (Appellant) v Secretary of State for Foreign and Commonwealth Affairs (Respondent) [2018] UKSC 3, Lord Kerr in his dissenting judgment cited with approval (at paragraph 103) the observations of Leggatt J in Gestmin:
…paras 15-22 have much to commend them… para 22 appears to me to be especially apt:
“… the best approach for a judge to adopt … is, in my view, to place little if any reliance at all on witnesses’ recollections of what was said in meetings and conversations, and to base factual findings on inferences drawn from the documentary evidence and known or probable facts. This does not mean that oral testimony serves no useful purpose – though its utility is often disproportionate to its length. But its value lies largely, as I see it, in the opportunity which cross-examination affords to subject the documentary record to critical scrutiny and to gauge the personality, motivations and working practices of a witness, rather than in testimony of what the witness recalls of particular conversations and events. Above all, it is important to avoid the fallacy of supposing that, because a witness has confidence in his or her recollection and is honest, evidence based on that recollection provides any reliable guide to the truth.”
A quick search for Gestmin and Leggatt J on BAILLI reveals a long list of cases where the observations in Gestmin on the unreliability of memory evidence have commended themselves to other judges. As Leggatt J himself notes (paragraphs 68 – 69) in Blue v Ashley (Rev 1) [2017] EWHC 1928 (Comm):
In some of these cases they were also supported by the evidence of psychologists or psychiatrists who were expert witnesses: see e.g. AB v Catholic Child Welfare Society [2016] EWHC 3334 (QB), paras 23-24, and related cases. My observations have also been specifically endorsed by two academic psychologists in a published paper: see Howe and Knott, “The fallibility of memory in judicial processes: Lessons from the past and their modern consequences” (2015) Memory, 23, 633 at 651-3. In the introduction to that paper the authors also summarised succinctly the scientific reasons why memory does not provide a veridical representation of events as experienced. They explained:
“… what gets encoded into memory is determined by what a person attends to, what they already have stored in memory, their expectations, needs and emotional state. This information is subsequently integrated (consolidated) with other information that has already been stored in a person’s long-term, autobiographical memory. What gets retrieved later from that memory is determined by that same multitude of factors that contributed to encoding as well as what drives the recollection of the event. Specifically, what gets retold about an experience depends on whom one is talking to and what the purpose is of remembering that particular event (e.g., telling a friend, relaying an experience to a therapist, telling the police about an event). Moreover, what gets remembered is reconstructed from the remnants of what was originally stored; that is, what we remember is constructed from whatever remains in memory following any forgetting or interference from new experiences that may have occurred across the interval between storing and retrieving a particular experience. Because the contents of our memories for experiences involve the active manipulation (during encoding), integration with pre-existing information (during consolidation), and reconstruction (during retrieval) of that information, memory is, by definition, fallible at best and unreliable at worst.”
In addition to the points that I noted in the Gestmin case, two other findings of psychological research seem to me of assistance in the present case. First, numerous experiments have shown that, when new information is encoded which is related to the self, subsequent memory for that information is improved compared with the encoding of other information. Second, there is a powerful tendency for people to remember past events concerning themselves in a self-enhancing light. [Footnoting Daniel Schacter, How the Mind Forgets and Remembers: The Seven Sins of Memory (2001)]
Elizabeth Loftus is a psychologist who has conducted ground-breaking research on witness memory. Professor Loftus’s TED talk, ‘How reliable is your memory?’ is fascinating viewing. In Cusack v Holdsworth & Anor [2016] EWHC 3084 (Ch) Mr Registrar Briggs observed (paragraph 25):
Memory is an active process, subject to individual interpretation or construction. Each witness will have produced their witness statements many months ago, will have been asked to read or re-read their statement and review documents before giving evidence in court. There is high level commentary that reveals that this process reinforces a memory, even if the memory was false to begin with, and may cause a witness’s memory to be based not on the original experience of events but on the material which has been read and re-read. This is supported by the recent research undertaken by Elizabeth Loftus, professor of law and cognitive science at the University of California which reveals the malleability of memory by showing that witness testimony can, after the fact, be shaped and altered.
Psychological research which is valid and relevant to witness evidence is always likely to spark interest from judges and lawyers and is potentially of assistance to fact-finders. However, despite the fact that lie detection has been ‘the subject of extensive research since the 1960’s’ (Denault & Jupe, 2018) there is very little research specifically about witness deception in the courtroom. Although there is extensive research-based practice guidance on questioning vulnerable witnesses (see for example the evidence-based guide Achieving Best Evidence in Criminal Proceedings, MoJ, 2011 and https://www.theadvocatesgateway.org ), there is nothing equivalent in relation to questioning (supposedly) ‘robust’ adult witnesses in court.  The English trial system draws heavily on witness evidence yet has only just begun to explore how psychological research could help the civil courts obtain and evaluate evidence from witnesses.


Dr Penny Cooper

Barrister at 39 Essex Chambers

Co-founder and Chair of The Advocate’s Gateway