Richard Posner's "What Do Judges and Justices Maximize?" (1993a) is not, as usually believed, the first analysis of judges' behaviors made by using the assumption that judges are rational and maximize a utility function. It arrived at the end of a rather long process. This paper recounts the history of this process, from the "birth" of law and economics in the 1960s to 1993. We show that economic analyses of judge behavior were introduced in the early 1970s under the pen of Posner. At that time, rationality was not modeled in terms of utility maximization. Utility maximization came later. We also show that rationality and incentives were introduced to explain the efficiency of Common Law. Around this theme, a controversy took place that led Posner, and other economists, to postpone their analysis of judicial behavior until the 1990s. By then, the situation had changed. New and conclusive evidence of judges' utility maximizing behavior demanded for a general theory to be expressed. In addition, the context was favorable to Chicago economists. It was time for Posner to publish his article.