Note: This is my fifth blog post in a month-long series on the basics of Bayesian probability theory.

Why do I prefer Bayes over Blackstone? It was over a century ago that the great Oliver Wendell Holmes invited scholars to look at the law through the lens of probability theory when he said: “The prophecies of what the courts will do in fact, and nothing more pretentious, are what I mean by the law.” But Holmes himself and few other scholars have taken up this intriguing invitation. As such, in place of previous approaches to the study of law (e.g. the study of the meaning of words or the canons of statutory interpretation), I will present a non-normative, mathematical approach to law and the legal process in the remainder of this series of blog posts.

Specifically, as I mentioned above, I will turn to Thomas Bayes, not William Blackstone, for inspiration and present a formal Bayesian model of civil and criminal litigation. That is, instead of focusing on the rules of civil or criminal procedure or substantive legal doctrine, we ask and attempt to answer a mathematical question: what is the posterior probability that a defendant in a civil or criminal trial will be found liable, given that the defendant has, in fact, committed a wrongful act? I will present my Bayesian model in my next few posts …