C. MacKay, ‘Landmark Jury Research Study Published’

Author: Charlie MacKay

The Scottish jury is something of a peculiarity compared with other juries of the common law world. It consists of 15 members (compared with 12 in those jurisdictions normatively closest to ours, such as England and Wales, Ireland, Canada, New Zealand and Australia), and only requires a simple majority of 8:7 for conviction. However, perhaps the greatest anomaly of the Scottish jury is that they have 3 verdicts at their disposal: ‘guilty’, ‘not guilty’ and ‘not proven’. The latter of these has been in our system since the 17th century and has persisted as a result of ‘historical accident.’ There have been calls for change in regards all 3 of these elements, however it is the ‘not proven’ verdict that has caused most public discussion.


On 10th October, the largest study into juries in the UK to date was published. A 2-year study involving 64 mock juries and 969 individual participants culminated in the Scottish Jury Research paper. The study was largely undertaken by two of the Professors of Criminal Law (and Criminal Justice) of the University of Glasgow – Professor James Chalmers and Professor Fiona Leverick, alongside Professor Vanessa Munro (University of Warwick), Rachel Ormston and Lorraine Murray (Ipsos MORI Scotland).


The study was commissioned following the Post-Corroboration Safeguards Review by Lord Bonomy in 2015. The Final Report, and the preceding Report of the Academic Expert Group, discussed the Scottish jury system and the potential for reform. However, the Report abstained from making substantive recommendations pending this research.


The Scottish Jury Research paper certainly makes for an interesting read. The study aimed to answer two questions: ‘What effects do the unique features of the Scottish jury system have on jury reasoning and jury decision-making?’ and ‘What are jurors’ understandings of the not proven verdict and why might they choose this verdict over another verdict?’ It used realistic methods, with jurors viewing video-recordings of mock trials approximately an hour long, before being asked to deliberate with other jurors for a maximum of 90 minutes. The variables were jury size, requirement for conviction and the verdicts available, with juries consisting of 12 or 15 jurors, consensus of verdict requiring unanimity or a simple majority and the jurors having 2 (‘guilty’ or ‘not guilty’) or 3 (both of the previous plus ‘not proven’).


The study found that all 3 variables impacted on individual juror verdicts, with key findings being that jurors were more likely to change their mind on the verdict in smaller juries, were more likely to return a guilty verdict if only a simple majority was required, and were less likely to return a guilty verdict if ‘not proven’ was available to them.

There is interesting discussion in the report as to jurors’ understanding of the ‘not proven’ verdict and its consequences. There are some views of the verdict that arouse concern, particularly considering the fact that judges are discouraged from attempting to explain the verdict to juries at trial. There is discussion of the potential for guidance for jurors to enhance their understanding of the legal and evidential elements of the criminal trial


The final Scottish Jury Research report is supplemented by two earlier reports on Methods of Conveying Information to Jurors and the Impact of Pre-Recorded Evidence on Juror Decision-Making.


This is obviously an extremely simplistic overview of the findings, and I would urge you to have a read of the report if you are interested in criminal law.


The report is a key contribution to the conversation regarding the controversial ‘not proven’ verdict, with Justice Secretary Humzah Yousaf stating ‘we will now engage in serious discussions on all of these findings including whether we should move to a two verdicts system.’ It will be interesting to see the long-term implications of the report, with the Post-Corroboration Safeguards Review regarding the 3 aspects of the Scottish jury system as inextricably linked, along with the corroboration requirement. It is clear that any reform would require in-depth reference to the Jury Research and substantial discussion of how best to achieve a balance in the Scottish jury.


The Scottish Jury Research paper can be accessed here.

The supplementary report on Methods of Conveying Information to Jurors is available here.

A summary of the supplementary report on the Impact of Pre-recorded Evidence on Juror Decision-Making is available here.

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