Major programme of mock jury research

Researchers from the School of Law at the University of Glasgow are about to embark on what will be the largest study of mock jury decision making ever undertaken in the UK. Professor James Chalmers and Professor Fiona Leverick are part of a team of researchers who have been commissioned by the Scottish Government to undertake research into various aspects of the way in which juries reach their decisions in criminal trials. They will be working with Ipsos MORI Scotland and Professor Vanessa Munro of the University of Warwick on the project, which commences this month and will last for two years. The project stems from the 2014 Post-Corroboration Safeguards Review (PCSR) led by Lord Bonomy, which considered whether additional safeguards against wrongful conviction might be needed in Scotland if the longstanding requirement for corroboration in criminal cases were to be abolished (as was recommended by the Carloway Review in 2011). A number of possible safeguards were considered by the PCSR, including reform of aspects of the jury system, but it recommended that a programme of research into jury reasoning and decision making should first be undertaken in order to inform any future decisions.

But why is this research necessary? A simple search for empirical research about jury decision making on any database will return hundreds of hits – there is certainly no shortage of existing studies. The answer is that, as Professor Peter Duff once put it, the Scottish jury is a “very peculiar institution”. It has three distinctive features: first, juries return verdicts by a simple majority of votes; secondly, juries have fifteen members; thirdly, juries have three possible verdicts open to them (guilty, not guilty, and not proven). In contrast, the common law world typically employs juries with 12 members, with the option of only two verdicts (guilty or not guilty) and which are required to return verdicts either unanimously or by a majority of at least 10 votes from 12. What this means is that the Scottish jury system is without direct counterpart elsewhere in the world, and so empirical and experimental research elsewhere is of limited applicability to Scotland.

The project has two components. The first will address a number of research questions relating to the distinctive features of the Scottish criminal jury, namely:

  • What jurors understand to be the difference between not guilty and not proven;
  • Why they choose one over the other;
  • Why, and to what extent, do jurors alter their position as regards not proven and not guilty as a result of deliberations;
  • The extent to which the members of a jury of 15 (as compared with a jury of 12) actually participate in deliberations;
  • The differences in outcome (assuming an identical factual matrix) as between a 12 person jury with only 2 possible verdicts and a 15 person jury with 3 verdicts, and the reasons for those differences; and
  • Whether there are benefits in requiring the jury to attempt to reach a unanimous verdict.

The study will not involve questioning jurors who have participated in actual criminal trials about their experiences of deliberation, which would be prohibited by section 8(1) of the Contempt of Court Act 1981. Instead, these questions will all be addressed via a large scale programme of mock jury experiments in which members of the public will be recruited to participate in simulated jury trials. A total of 64 mock juries will be assembled, each broadly representative of the jury eligible population. Each mock jury will watch a filmed trial, designed to be as realistic as possible, and will then be asked to deliberate in order to reach a verdict. Case simulation research has advantages which are particularly important in the context of this research: it allows researchers to manipulate specific variables (such as the availability of two or three verdicts) while holding other factors constant.

The second component of the research will address two further questions, namely (a) what are the most effective approaches for aiding jury comprehension of trial proceedings and the evidence presented and (b) whether jurors perceive pre-recorded evidence given by children and vulnerable witnesses differently from evidence given in a court. These questions, which are not contingent on the particular features of the Scottish jury, will be addressed via reviews of existing research evidence.

~ James Chalmers and Fiona Leverick

James Chalmers is Regius Professor of Law and Fiona Leverick is Professor of Criminal Law and Criminal Justice at the School of Law.

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