Bayes and the Law

Although the use of statistics in legal proceedings has considerably grown in the last 40 years, primarily classical statistical methods rather than Bayesian methods have been used. Yet the Bayesian approach avoids many of the problems of classical statistics and is also well suited to a broader range of problems. This article reviews the potential and actual use of Bayes in the law and explains the main reasons for its lack of impact on legal practice. These reasons include misconceptions by the legal community about Bayes' theorem, overreliance on the use of the likelihood ratio, and the lack of adoption of modern computational methods. We argue that Bayesian networks, which automatically produce the necessary Bayesian calculations, provide an opportunity to address most concerns about using Bayes in the law.