Veridical Verdicts: Increasing Verdict Accuracy Through the Use of Overtly Probabilistic Evidence and Methods

Abstract:     
One cannot determine the merits of using base rate evidence and subjective probabilities without stipulating the underlying purposes in structuring trials. Yet commentators have not always distinguished clearly between verdict accuracy and what we will term 'policy concerns' (i.e., policies distinct from verdict accuracy that are implicated by trials). Instead, they often have let their views about one dictate their views about the other. Since the two are conceptually distinct, however, it is useful to consider separately the implications of probabilistic evidence for each in order to identify and evaluate the tradeoffs that may be involved. This Article will perform the first half of the necessary analysis by examining the effect of overtly probabilistic evidence and methods on verdict accuracy. We will show that overtly probabilistic evidence is no less probative of legally material facts than other types of evidence. We will suggest, moreover, that rules of probability theory such as Bayes' theorem can improve the accuracy with which juries evaluate evidence in particular cases, even when applied (where feasible) to subjective probabilities. Section I of this Article discusses the basic terms involved in a consideration of overtly probabilistic evidence. Section II considers the significance for verdict accuracy of using base rate evidence. Section III discusses the use of subjective probabilities. Section IV discusses problems with the use at trial of probabilistic evidence and methods. Section V provides a summary and conclusion.

Number of Pages in PDF File: 33

Keywords: Base rate, probability, evidence

Accepted Paper Series