In the United States, judges use “pattern instructions” to inform jurors of laws relevant to the case at hand, and for the procedures they are to use in order to carry out their duties. Although these instructions are written in a legally accurate manner, social science research has demonstrated that they are often not well understood by jurors, who consequently render decisions based on an incomplete, or inaccurate, understanding of the law. This chapter reviews factors that lead to comprehension problems associated with judicial instructions, including: the language and sentence structure typically used to write instructions, jurors’ education level and life experiences that contribute to preexisting beliefs about the law, and trial complexity. The chapter also reviews the effectiveness of solutions that have been proposed for improving jurors’ understanding of judicial instructions, so that more legally accurate decisions can be rendered.

Chapter 4 examines jury instructions, which are given orally by the judge to provide guidance to the jurors, including an understanding of the relevant law. The traditional view of jury instructions is that jurors are rational problem-solvers who just need to be told the law to apply. According to the transformation view, however, the reading of the instructions provides an experience for the jurors that is far more than simply the conveyance of information about the law. The judge’s reading of the instructions as the jurors sit together in the jury box ensures that all of the jurors hear the instructions from start to finish, as a group, and that everyone in the courtroom, including the jurors, senses the important role the instructions play. If jury instructions are understood as part of the jury process of helping jurors to assume their role as jurors, then the oral reading by the judge needs to be supplemented by certain aids so that jurors understand the substance of the instructions. Jurors need to be given an individual written copy of the instructions; they should be permitted to take notes, and to submit written questions about the instructions to the judge.

This chapter examines the issue of how well Canadian jurors comprehend legal instructions and whether there are jury aids that can enhance their comprehension. It traces the design of the first study in Canada to assess the relative efficacy of two competing styles of instructions used in Canada and to compare them with the plain language criminal law instructions used in California, USA. The style that used a series of logical questions to be answered was associated with the highest levels of comprehension. The results also revealed that the type of aid provided had a modest impact on overall comprehension score and that those who received either both aids (written instructions and decision trees) or written instructions had scores that were significantly different from either those with no aid or the decision tree alone. This chapter also explores some of the challenges associated with cross-jurisdictional research. Additional studies are needed to ensure that jurors have an accurate understanding of the law and to make clear how styles of jury instruction and jury aids can impact comprehension levels.