Scottish Jury Research

Findings of UK’s largest ever mock jury study published.

Major research into how juries reach decisions has found that the size of the jury, the number of verdicts available and the type of majority required may all have an effect on the outcome of finely balanced trials.

The study of Scotland’s jury system, in which cases are heard by 15 jurors with a choice of three verdicts returned by a simple majority, suggests that:

• reducing jury size from 15 to 12, as is the norm in most English language jurisdictions, might lead to more individual jurors switching their position towards the majority view
• asking juries to reach a unanimous or near unanimous verdict might tilt more jurors in favour of acquittal
• removing the not proven verdict might incline more jurors towards a guilty verdict in finely balanced trials

It also found inconsistent views on the meaning of not proven and how it differed from not guilty.

Commenting on the research, Justice Secretary Humza Yousaf said:

“I am grateful to everyone who gave up their time for this major piece of research, which is just one part of our work to improve Scotland’s justice system for all.

“We will now engage with legal professionals and the wider public to consider all of the findings. We are organising events around the country and I am keen to hear from a wide range of people, especially those with personal experience of the criminal justice system.

“In particular, we will now engage in serious discussions on all of these findings including whether we should move to a two verdicts system. My mind is open and we will not pre-judge the outcome of those conversations.”

The research was undertaken on behalf of the Scottish Government by Ipsos MORI Scotland and researchers from the Universities of Glasgow and Warwick.

Nearly 1,000 people took part in the jury research. This included 863 of these participants being ‘mock jurors’ in one of 64 staged jury deliberations, with each watching a video of either a Scottish rape or assault trial.

The fictional but realistic trials were finely balanced, in order to encourage debate about guilt and acquittal, and to maximise the likelihood that jurors would consider the difference between the not guilty and not proven verdicts.

Rachel Ormston, Research Director at Ipsos MORI, said: "It was a privilege to be involved in the most extensive programme of mock jury research carried out in the UK. The report presents detailed findings on how the unique features of the Scottish system impact on juror decision-making, and as such will allow decisions about any potential future changes to be taken on the basis of robust evidence."

Fiona Leverick, Professor of Criminal Law and Criminal Justice at the University of Glasgow, said: "In shining a light on the ways in which jurors understand and use the not proven verdict, this study will help inform ongoing debates about this verdict. It also provides insight into areas where jurors may require additional support or guidance to avoid legal misunderstandings."


Scottish Jury Research: Findings From a Large-Scale Mock Jury Study involved 64 mock juries and 969 individual participants. It is the first to consider the unique nature of the Scottish jury system with 15 jurors, three verdicts and a simple majority. The report sets out the researchers’ findings but does not make any recommendations.

The study was commissioned by the Scottish Government in response to Lord Bonomy’s Post Corroboration Safeguards Review, which recommended that research should be carried out to ensure that any changes to Scotland’s jury system should be made only on a fully informed basis, including the impact having a three verdict system has on decision making.
Two detailed evidence reviews were also published in 2018 as part of this research project:
• a review of ways in which juror communications might be improved
• a review on the impact on juror decision-making of pre-recorded evidence and live-link testimony by child and vulnerable adult witnesses in criminal trials



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