The great debate over formalism and realism has a tortuous history. It was the jurisprudential debate of twentieth-century American legal theory, and it continues, rehashing old moves, relabeling old positions, and — this is the hopeful bit — exhibiting new, surprising, and productive developments. One of those productive developments has been the turn to rigorous methods in positive legal theory. Contemporary legal theory is increasingly influenced by methods and ideas imported from the social sciences — a development that is part of a larger trend in the legal academy: interdisciplinarity. Some of this story is old hat by now. Law and economics and the law and society movement entered the legal academy long ago. Other parts of the story are new. Today, interdisciplinary approaches to legal theory include the transplantation of empirical methods for the study of judicial behavior from political science, the application of the game-theoretic models developed under the rubric of positive political theory (PPT) to the strategic interactions among judges and between judges and the political actors who select them and react to their decisions, and the nascent emergence of experimental jurisprudence (or “X-Jur”), which applies experimental techniques developed in psychology and cognitive science to the problems of legal theory.
One of the most promising trends has been the gradual erosion of the wall of acoustic separation that insulated lawyers, judges, and legal scholars from the rich body of empirical work on judicial behavior developed by political scientists, represented by the so-called “attitudinal model,” pioneered by Professor C. Herman Pritchett and famously associated with the work of Professors Harold Spaeth and Jeffrey Segal, among many others. The core idea of the attitudinal model is that ideology (and not the law) is the most important determinant of judicial behavior. The rise of the attitudinal model in political science was anticipated and influenced by the American legal realists, a loosely defined group of judges, lawyers, and scholars, who marked the difference between the “law in action” and the “law in books” and formulated early versions of what is now called “the indeterminacy thesis” associated with the critical legal studies (CLS) movement. Like the attitudinalists in political science, critical scholars who embraced the indeterminacy thesis contended that politics, not law, is the primary determinant of judicial behavior.
But attitudinalism and PPT in political science and CLS in law were not the only heirs of realist skepticism about the determinacy of law. Judge Richard Posner’s influential 1993 article, What Do Judges and Justices Maximize? (The Same Thing Everybody Else Does), proposed a model of judicial behavior that viewed judges as rational maximizers, whose decisions are explained by a utility function that included leisure time and pecuniary income. Posner’s model eliminated ideology as a direct consideration in judicial decisionmaking: “My approach downplays the ‘power trip’ aspect of judging, the focus of most of the few previous efforts to model the judicial utility function. In fact, I assume that trying to change the world plays no role in that function.” And law itself played no role in Posner’s model. His skepticism about the role of law in legal decisionmaking is further illuminated by his essay for the one hundredth anniversary issue of the Harvard Law Review, in which he argued that legal theory had failed to develop tools for the interpretation of legal texts, with the consequence that statutory interpretation (and by implication, the interpretation of constitutions, rules, regulations, and even judicial opinions) is indeterminate. Posner later wove the various strands of his thought into the tapestry he calls “pragmatism,” articulated most fully in his magnum opus, How Judges Think.
Posner assumed that policy preferences play “no role” in the determination of judicial behavior, but his economic approach to judicial behavior was nonetheless in the rational choice tradition: rational choice theories explain judicial behavior on the basis of the preferences of individual judges. In political science, the rational choice paradigm was combined with game theory in what is called “positive political theory.” Unlike the attitudinal model (which predicts the behavior of an individual judge based only on that judge’s preferences), PPT models of judicial behavior take strategic interactions between judges into account. For example, the behavior of a Supreme Court Justice is not just a function of the policy preferences (or ideology) of the individual Justice in isolation. The Justices must take the preferences of their colleagues into account; only by modifying their positions can they get five votes and thereby shape the content of the law.
PPT approaches to judicial behavior frequently employ “pivotal politics” models, originally developed in the context of modeling legislative behavior. According to these models, in the House of Representatives, the member whose ideological views are at the median (with equal numbers of colleagues to the left and the right) is the “pivot,” the member whose vote will determine whether bills brought to the floor will pass or fail. On a collegial court like the Supreme Court, we call the vote of the pivotal Justice the “swing vote” — in cases where the swing vote will determine the outcome, the opinion writer must write an opinion that will attract the vote of the pivotal Justice to form a majority. Pivotal politics models identify these key players, the “pivots” whose preferences define which outcomes are possible (assuming, of course, that the models are confirmed). While Posner’s model assumed that policy preferences play almost no role in shaping judicial behavior, PPT models assume the opposite — that policy preferences are the driving engine of judicial behavior.
On the surface, it might seem that progressives from the 1930s, radical legal scholars from the 1980s, a conservative federal judge, and (supposedly) value-neutral social scientists have little in common. But there is a common thread. As Judge Harry Edwards and Professor Michael Livermore put it: “The theories underlying the attitudinal model, legal realism, critical legal studies, and pragmatic adjudication share the view that the law generally does not constrain judges in their decisionmaking because it does not provide clear answers.” This shared view or common assumption can be expressed as the “indeterminacy thesis,” the key realist move in the grand debate with formalism.
Enter The Behavior of Federal Judges: A Theoretical and Empirical Study of Rational Choice (or Behavior of Federal Judges for short or Behavior for really short), a magisterial and important book, co‐authored by Lee Epstein, who was trained as a political scientist and who is currently appointed in law and political science at the University of Southern California; William Landes, trained as an economist and currently on the faculty at the University of Chicago Law School; and Richard Posner, trained as a lawyer and currently a judge on the United States Court of Appeals for the Seventh Circuit. Although the subtitle of Epstein, Landes, and Posner’s book is A Theoretical and Empirical Study of Rational Choice, the emphasis is decidedly on the empirical — with theory getting the short shrift. Chapters two through eight, which consume 320 of the 422 pages or about 75% of the total, summarize the literature on judicial behavior and present important new empirical findings. Theory (with a corresponding economic model) appears in chapter one, entitled “A Realistic Theory of Judicial Behavior,” which presents an updated version of Posner’s 1993 model of judicial behavior, now recast as a labor economics model (pp. 25, 48) and self-described as a summary of Posner’s How Judges Think (p. 25).