A Formal Model of Legal Proof Standards and Burdens

This paper presents a formal model that enables us to define five distinct types of burden of proof in legal argumentation. Four standards of proof are shown to play a vital role in defining each type of burden. These standards of proof are defined in a precise way suitable for computing in argumentation studies generally, but are based on a long tradition of their use in law. The paper presents a computational model based on these notions that represents a dialectical process that goes from initial claims where issues to be decided are set, and produces a justification for arriving at a decision for one side or the other that can withstand a critical evaluation by a particular audience. The role of the audience can be played by the respondent in some instances, or by a neutral third party audience, depending on the type of dialogue. The paper builds on previous work (Gordon, Prakken and Walton, 2007; Gordon and Walton, 2009) that has applied the Carneades model to studying burden of proof in legal argumentation.