Edinburgh Napier University

  The Scottish Legal system is a unique jurisdiction as jurors are able to give Not Proven verdicts in addition to the well-known Anglo-American verdicts (Guilty and Not Guilty). The Not Proven verdict has never been legally defined, meaning that currently legal practitioners can only estimate why a Not Proven verdict has been given. The main aim of this study was to investigate if jurors violate the regularity principle, which is commonly incorporated in many rational choice models, by testing if the introduction of the Not Proven verdict has an impact on the outcomes given by jurors. In addition, this study aims to test if the introduction of the Not Proven verdict has an impact upon how the Not Guilty verdict is perceived by jurors. In this study, 128 participants listened to two vignettes centred on homicide trials, jurors could give one of two verdicts in one of the vignettes and one of three verdicts in the other vignette. The vignettes were counterbalanced in regard to how many verdicts could be given at the end of them. It was found that jurors in a three-verdict system were less likely to give a Not Guilty verdict in comparison to jurors in a two-verdict system, showing that jurors violate the regularity principle and that the Not Proven verdict may change how the Not Guilty verdict is perceived. The current paper has implications in relation to juror communication, article six of the European convention of human rights and juror rationality.