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The value and progress of jury research in Scotland

Updated Thursday, 18 May 2023

Professor James Chalmers reports on the findings - and questions - brought about by the Scottish Jury Research project.

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This content is part of our Jury Hub.


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When the Scottish Government announced in 2015 that it had accepted a recommendation to commission research into the Scottish jury, an observer might have wondered why this was even necessary. In 2012, Dennis J Devine estimated that there had been 1500 jury research studies carried out by 2011. Is there really anything new to learn?


The answer is perhaps “always”, but the gaps in our knowledge are especially acute in Scotland because of the unique features of the Scottish jury system. Most jury research – where it involves jurors deliberating in groups rather than research which asks individual participants to reach decisions – is structured around the traditional common law jury. That jury has 12 members, elects between verdicts of guilty or not guilty, is required to reach verdicts either by unanimity or something close to it, and can “hang” (fail to reach a verdict, permitting a retrial) if it fails to reach that threshold. The Scottish jury, by contrast, has 15 members, a third verdict of “not proven”, and reaches verdicts by a simple majority – and so never hangs. Without eight votes in favour of a guilty verdict, the outcome will always be an acquittal.


All this means that the vast body of jury research worldwide is, if we seek to rely on it in the Scottish context, vulnerable to the objection that things might be different here. Does a jury of 15, for example, work in the same way as a jury of 12? Even where researchers have asked questions about jury size they are ones which barely arise in the Scottish context. Many US researchers have examined, for example, whether a jury smaller than 12 deliberates as effectively as one of 12 – a seam of research prompted by court decisions on the constitutionality of a smaller jury. But while that research demonstrates clearly that size matters, and that there are significant risks in reducing the size of the jury downwards from 12, the space between 12 and 15 remained unexplored.


In commissioning the Scottish Jury Research, the government sought to fill that gap, asking the researchers to examine via mock jury research what difference the unique features of the Scottish jury made in comparison with the traditional common law jury. The results of the research are detailed elsewhere, but particular attention has focused on Scots law’s “not proven” verdict, where the research found that individual jurors were less likely to favour a guilty verdict where the option of not proven was available. That sits alongside a body of other research, which has grown in recent years, examining that verdict, and which has contributed to the decision of the Scottish Government to bring forward legislation abolishing it.


Even a project as large as the Scottish Jury Research only contributes incrementally to what we know, however. It might be tempting to think that a research project can tell us “how the jury works”, but a properly designed mock jury study must be tightly focused. The Scottish research was designed to answer a specific set of research questions, drawing on two specific trial scenarios. The insight the research produces is genuine, but the variety of cases which come before the courts is far greater than the two scenarios tested.


In some jurisdictions, it is possible to carry out research with real jurors about their deliberations. Such research is currently not possible within the United Kingdom jurisdictions, because the law prohibits asking jurors about their deliberations. It is possible to ask real jurors about aspects of their experience other than their deliberations, or to invite them to participate in other research such as attitudinal surveys or mock jury research. This has the advantage of ensuring that the research participants are representative of real jurors although, as with all mock jury research, is subject to the limitation that the participants are no longer, at the time of the research, “real jurors”: they know that they are not deciding a real case and that their decisions will not have real-world consequences.


Research asking real jurors about their deliberations would help to build a richer picture of how juries in Scotland (and the rest of the United Kingdom) discharge their task, but would require legal sanction which is currently unavailable to researchers. Should such work become possible, it would provide a valuable complement to the body of knowledge which mock jury research has provided in recent years.


That said, however much information is obtained from jury research, care should be taken before assuming it provides an answer as to how the jury should operate. The Scottish Jury Research, for example, suggests that Scotland’s not proven verdict makes convictions less likely – although cannot quantify its real world effect with precision. But because jury research cannot readily tell us how often juries should convict, demonstrating that a particular change might increase or decrease the conviction rate does not tell us whether that change would be a good or a bad one. Instead, researchers must be able to work with policy makers and lawyers to explain their work and to facilitate discussions, research-informed but based on first principles, as to what the role of the jury should be and how its task should be discharged. Abolition of the not proven verdict, for example, cannot be justified simply in terms of its effect on conviction rates, but instead on a principled discussion of the rights and wrongs of providing a jury with two options for verdicts of acquittal which are nominally different but with identical legal consequences.


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