Case comment: responding to the implausible, incredible and highly improbable stories defendants tell: a Bayesian interpretation of the Venray murder ruling

In criminal trials, defendants often offer alternative explanations of the facts when they plead for their innocence. In its ruling on the Venray murder case, the Dutch Supreme Court dealt with the question when and how courts can reject such alternative explanations. According to the Supreme court, while courts should typically refer to evidence that refutes the explanation, they can also argue that the explanation ‘did not become plausible’ or that it is ‘not credible’. Finally, courts can state that an explanation is so ‘highly improbable’ that it requires no response. However, the Supreme Court did not explain these terms, leading to confusion about how they ought to be interpreted. This case comment offers a Bayesian interpretation according to which these three terms relate to (i) the posterior probability of the explanation, (ii) the credibility of the defendant, and (iii) how obvious it is that the explanation is improbable. This interpretation clarifies the Supreme Courts ruling and ties it to the criminal law system’s goals of error minimization and of producing understandable decisions efficiently.