Accuracy, optimality and the preponderance standard

作者：Cheng Edward K^*; Pardo Michael S

来源：Law, Probability and Risk: A Journal of Reasoning under Uncertainty , 2015, 14(3): 193-212.

DOI：10.1093/lpr/mgv001

• burden of proof
• burden of persuasion
• evidence
• accuracy
• welfare
• minimax
• error

Law-and-economics scholars have recently argued that the legal system should set burdens of proof on the basis of ex ante welfare considerations. In this article, we reject this welfarist approach, showing that it relies on contested normative principles, raises legitimacy concerns, and is nearly impossible to implement in practice. As an alternative, we propose a decision-theory model that we constrain to account for core legal values and the practical limitations of the trial process. Specifically, we require that the burden of proof prioritize accuracy (truth) over welfare, and that it be capable of operating without knowledge of the base rates or prior probabilities of activities. The resulting optimization problem can be solved using a minimax approach, which minimizes the maximum probability of error faced by each of the parties, and remarkably, the minimax solution turns out to be precisely the preponderance-of-the-evidence standard currently imposed by courts. We thereby not only refute recent welfare theories about the burden of proof, but also provide a new theoretical justification for the traditional preponderance standard.

• 出版日期2015-9