Pre-recorded evidence and juror decision-making: evidence review

Paper on the impact on juror decision-making of pre-recorded evidence and live-link testimony by child and vulnerable adult witnesses in criminal trials.

Executive Summary


In recent years, a growing interest has been expressed by many practitioners and policy-makers within the Scottish criminal justice system in making greater and more effective use of digital technology in the courtroom, particularly – but not necessarily exclusively – in relation to the delivery of testimony by child and vulnerable adult witnesses. Provision already exists in Scotland for live-links to be utilised in order to avoid witnesses having to come into court to give evidence, for prior statements or recorded police interviews to be submitted as evidence-in-chief, and for testimony to be taken and recorded ahead of time by a court-appointed commissioner. However, to date, applications to make use of pre-recorded testimony have been rare.

Perceived Risks and Benefits of Pre-Recorded Evidence

Research has demonstrated that both child and vulnerable adult witnesses appreciate the opportunity to give testimony in alternative ways designed to ameliorate the stressors associated with giving evidence in the courtroom in the presence of the accused. Despite this, criminal justice practitioners have often highlighted concerns regarding the extent to which the use of live-links and pre-recorded testimony can influence jurors’ credibility assessments and, ultimately, their verdict decisions. Some have worried that allowing witnesses to give testimony outside of the courtroom sends a signal to jurors about an inability to face the accused, which can either be interpreted as re-enforcing the truth of the allegation or – conversely – as implying the witness’ knowing deception. Others have suggested that the presentation of the witness on a TV screen reduces jurors’ ability to read body language in order to pick up on non-verbal cues of deception or veracity; while others have worried that evidence presented on a TV screen will be less vivid and have less (emotional) impact than live testimony. The aim of this Evidence Review is to evaluate the existing research that tests the legitimacy of these concerns. It considers evidence in relation not only to witnesses’ use of pre-recorded testimony at trial, but also live-link facilities, since it is often difficult to clearly disentangle the effects of the TV screen medium itself from the effects associated with the timing and conditions of the actual testimony.

Scope of the Review

The primary focus is on studies that have sought to generate ‘first hand’ insight into the dynamics and substance of jury deliberations, rather than those which have interviewed practitioners about what they hypothesise influences jury decision-making. While this latter form of evidence can provide a useful point of triangulation, it does not provide a robust foundation for understanding the dynamics and content of collective discussions within the jury room. In a context in which many jurisdictions have imposed legal restrictions on the direct questioning of real jurors about their deliberations, a variety of simulation techniques have been developed. These seek to provoke responses to trial scenarios from third party observers, which can be analysed in order to increase our understanding of jury decision-making. As will be discussed in Chapter Two, such simulation studies present distinctive methodological challenges, but – when carefully designed with an eye to the realism of the trial environment – they provide useful insights which can, at least in some cases, be cautiously extrapolated from to catch a glimpse of what goes on within the jury room.

The Review draws upon experimental studies, mostly from the 1990s onwards, based on an extensive literature review of English language publications across a range of UK, Commonwealth and European jurisdictions. It spans Government evaluations, reports by independent research institutes, and peer-reviewed studies conducted by academic researchers, often but not exclusively published within psychology journals. A prioritised focus has been given to research studies that rely on the most rigorous methodologies, arise in legal systems of most relevance to Scotland, and / or have been conducted most recently, on the basis that these hold most evidential weight.

Use of Pre-Recorded Evidence by Child Witnesses

A number of studies have focused on the impact of the use of special measures in general, and live-links and pre-recorded testimony in particular, by child witnesses. Broadly speaking, these have demonstrated that – contrary to many people’s misplaced confidence in their ability to do so – jurors are not in fact significantly better able to reach the truth and discern signs of deception when children testify in open court as compared to testifying via live-link or pre-recorded testimony. Moreover, while some – but by no means all – studies have suggested that jurors may prefer children’s testimony to be delivered live in court, there is no clear evidence that this impacts in any significant way upon verdict outcomes. The existence of group deliberation appears to be key in this respect, reducing any pre-deliberation propensity on the part of individual jurors to rate less highly the credibility and likeability of child witnesses who give evidence via live-link or pre-recorded video. Research in this area has also established, however, that findings in respect of child witnesses are complicated by the interaction of mode of evidence delivery with factors such as the perceived emotionality of the child, his or her age and level of understanding, and jurors’ preconceptions regarding the reliability of children’s memory, particularly over time.

Use of Pre-Recorded Evidence by Vulnerable Adults Witnesses

While fewer studies have been conducted on the use by adults of pre-recorded evidence, research involving fairly sophisticated rape trial simulations has indicated that the level of any impact upon mock jurors is low, and its direction unpredictable. The use of special measures may increase one person’s empathy for an adult rape complainer at the same time that it raises another’s suspicion about her credibility in equal measure. Beyond sexual offence trials, existing research is extremely limited. Some studies suggest that mode of testimony may have a stronger influence, which can work against witnesses, but it is difficult to place confidence in these findings due to certain weaknesses in their underlying methods: in particular, their failure to incorporate a group deliberation stage, which has been shown - both in relation to child witnesses and adult rape complainers - to perform a key role in neutralising individual influences, so as to counteract any significant impact of testimony mode on verdict outcomes.

Complicating Factors in Comparing Studies

Comparing findings in relation to the influence upon jurors of the use of pre-recorded evidence is complicated by the fact that such testimony is introduced in different ways across studies, and across legal systems. Much of the research on child witnesses has relied on one-way CCTV links (in which the advocates and judge relocate to a remote room to take the witness’ testimony, which is then relayed to jurors and the accused in the courtroom), rather than two-way transmissions in which counsel and the judge also remain in the courtroom.

Likewise, while some of the studies exploring the effects of pre-recorded evidence have relied on videos of pre-trial depositions in which witnesses are asked questions by counsel on both sides ahead of time in the presence of a judge, others have utilised videotapes of forensic interviews, often completed nearer the time of the alleged incident by police officers.This variability in the ways in which pre-recorded evidence is introduced to jurors can make extrapolating findings across studies more complicated and may make predictions regarding its impact upon jurors more jurisdictionally-specific.

Using Pre-Recorded Evidence in Practice

There are additional factors associated with the way in which live-link or pre-recorded evidence is operationalised at trial which may also interact with the influence upon jurors associated with the mode of testimony per se. The length and format of police forensic interviews have, for example, been suggested to have a significant effect, but the existing evidence is somewhat inconclusive. What is more clear is that jurors are prone to be distracted by the poor audio and visual quality of live-links and pre-recorded evidence when they are used in many courtrooms, and that factors such as the choice of camera perspective may bear careful scrutiny for their potential to influence jurors’ assessments of witness credibility. If current calls to make greater use of such testimony are to be acted upon in Scotland, it is incumbent upon policy-makers and practitioners to ensure that they are introduced within interview contexts and courtrooms in a manner that prevents undue influence upon jurors.


While there is a need for further, and more methodologically rigorous, research in this area, particularly in relation to adult witnesses, the existing evidence does not establish a significant risk of negative juror influence associated with the use per se of pre-recorded testimony by either child or adult witnesses. Some – but by no means all – studies suggest a preference on the part of jurors for evidence that is presented live in court, but in simulations with a group deliberative component, mimicking actual jury decision-making, the broad consensus of researchers to date has been that this preference does not impact significantly upon verdict outcomes.


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