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This article will focus on how jurors understand and apply expert testimony as presented during adversarial trial proceedings and how those proceedings pose challenges for them. It will also explore the possibility that both understanding and application can be enhanced if the presentation and structure of expert testimony is changed.

Part II of this article will describe the extent of experts’ “reach,” focusing particularly on experts who testify about scientific and technical matters. This section details the frequency with which these experts testify in trials in the United States and the types of trials in which they are involved. We adopt the framework used by social psychologists to capture the elements of persuasion inherent in expert testimony, including attention to the communicator (the expert witness), message (the testimony itself), and audience (jurors and juries).

Part III will evaluate what psychologists and other social scientists have learned about laypeople’s use of expert testimony. On the one hand, there is reason for cautious optimism given jurors’ relatively careful scrutiny of experts’ information and objectives. On the other hand, jurors experience difficulties in understanding and using probabilistic and statistical expert evidence.

Part IV introduces a novel concept regarding the presentation of expert testimony, namely hot tubbing, also referred to as concurrent evidence presentation. In this process, expert witnesses with differing positions reconcile some of those differences out-of-court and then testify concurrently, or immediately after one another, about ongoing disagreements. This procedure is primarily used in administrative hearings and tribunals in Australia and New Zealand, and on rare occasions during hearings in federal court in the United States. Hot tubbing challenges the standard chronology of adversarial trial proceedings. It confers various putative advantages, but also raises some concerns.

Part V covers some practical considerations associated with concurrent evidence presentation. On balance, we believe that hot tubbing will enhance jurors’ understanding of expert testimony and lead to more rational and predictable verdicts, particularly in cases involving complex and probabilistic evidence

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