Abstract
Richard A. Posner was the most important actor in the transformation from "law and economics" to an "economic analysis of law". Posner applied Chicago price theory to the analysis of law and legal rules. He not only contributed to the field but also structured it. This is what this chapters shows. We also show that Posner's work illustrates the Chicagoan dimension of his economic analysis of law. That Posner, especially later in his career, introduced some elements that might seem to be at odds with Chicago economicspragmatism, notably-or that he claimed having become a Keynesian does not change much to the claim that it was Posner who crafted Chicago's economic analysis of law.