Taking a page from the law books: Considering evidence weight in evaluating assurance case confidence

This brief report is a contribution to discussions of the notion of confidence in the context of assurance cases. In this work, we draw a parallel between the concepts of assurance case confidence and evidence weight in the legal domain, and explore the practical ramifications of this idea. We first establish what factors influence assurance case confidence, and propose a definition. Then, through a comparison with the legal domain (following the discussions of Jonathan Cohen, Keynes and Nance) we submit that confidence can be seen as composed of two distinct aspects, and we proceed to contend that it is beneficial to consider these aspects separately when performing an evaluation. One of the greatest advantages of doing so would be providing a separate measure for assurance case “ripeness” for review (to be used by assurance case developers, as well as regulators).