Information economics in the criminal standard of proof

In this paper we model the criminal standard of proof as a twofold standard requiring sufficient probability of the factum probandum and sufficient informativeness. The focus of the paper is on the latter requirement, and we use decision theory to develop a model for sufficient informativeness. We demonstrate that sufficient informativeness is fundamentally a question of information economics and switch-ability. In our model, sufficient informativeness is a cost-benefit-analysis of further investigations that involves a prediction of the possibility that such investigations will produce evidence that switches the decision from conviction to acquittal. Critics of the Bayesian approach to legal evidence have claimed that ‘weight’ cannot be captured in a Bayesian model. Contrary to this claim, our model shows how sufficient informativeness can be modelled as a second order probability.