Decision Theory and Proof Standards for Future Crimes: Possible Uses and Open Questions.

What should be the proof standard for applying preventive criminal sanctions based on an establishment of risk of reoffending? This is an open question in legal systems around the world. Various authors suggest that we can answer it by using decision theory. This approach conceptualises the proof standard as a probabilistic threshold. A person can then only be subjected to a preventive sanction if the probability that they will commit a crime in the (near) future is sufficiently high. How high this probabilistic threshold should be set depends mostly on the relative utilities that society assigns to errors (preventive sanctions applied to non-dangerous individuals and dangerous individuals to whom no sanction is applied). This article explains the problem of unclear standards of proof for future crimes, offers a non-technical explanation of how decision theory may help solve this problem, surveys existing work on this topic, and outlines several questions and worries that require further academic attention.