1. Introduction A stark contrast exists between the widespread application of positive political economy models in the study of the executive and legislative branches of government and the relative dearth of such work on the judiciary. In particular, the U.S. Supreme Court is widely regarded as a totally independent body whose rulings are not influenced by political or other outside pressures. Indeed, the dominant political science model of Supreme Court decision making, the attitudinal model, argues that the rules and structures of the U.S. political system allow justices to vote sincerely without constraints from Congress and/or the president (Segal and Spaeth 1993). In contrast to this dominant view, several authors have begun to analyze Supreme Court decisions guided by the positive models of bureaucratic behavior that exist in both the economics and the political science literature. Toma (1991) finds that Congress signals its opinion of the Court's direction through budgetary allocations, and that budget changes have a significant effect on Court decisions. Her more recent work (Toma 1996) focuses on the role of the chief justice as an agent of Congress who reacts to budgetary signals to bring Court decisions in line with congressional preferences. Spiller and Gely (1992) find strong evidence of congressional influence over Court decisions in industrial labor relations cases. Caporale and Winter (1998) find support for the existence of both executive and congressional influence over Supreme Court decisions in criminal procedure cases. This paper investigates possible outside influences on Supreme Court decisions in economic cases. We find that Republican presidents and more conservative leadership of the Senate and House Judiciary Committees are significantly correlated with more conservative Supreme Court economic decisions. In addition, we find that conservative decisions are positively correlated with the fraction of the Court appointed by Republican presidents. This provides strong support for a presidential of appointment channel of judicial influence. Also, we find that the lagged inflation rate significantly influences the direction of the Court's economic decisions. Finally, we demonstrate the robustness of our results using an alternative measure of congressional ideology. 2. Theories of Supreme Court Behavior The Traditional Legal Model Courts are the mere instruments of the law, and can will nothing. When they are said to exercise discretion, it is a mere legal discretion, a discretion to be exercised in discerning the course prescribed by law; and, when that is discerned, it is the duty of the Court to follow it. Judicial power is never exercised for the purpose of giving effect to the will of the Judge; always for the purpose of giving effect to the will of the Legislature; or, in other words, to the will of the Law. Chief Justice John Marshall, 18241 As recent legal analysts have noted, the vast bulk of legal scholarship and content of law school training largely rests on Justice Marshall's contention.2 Explicitly or implicitly, an assumption is made that court decisions are based centrally on reasoned arguments. This view, in which judges apply neutral principles and logical reasoning to the Constitution, prior precedents, or statutes in resolving cases is labeled the legal Perhaps the clearest proponent and strongest advocate of the traditional model was Christopher Columbus Langdell, the Harvard Law School's first dean.3 For the Langdellian judge, judicial decisions are based on logical reasoning or reasoning by example. Primary importance is placed on textual interpretation and legal precedent. From this framework, decisions can be viewed as inevitable conclusions based on the analysis of earlier cases. Clearly, this model left no room for any expression of judicial individuality or personal ideology. The Attitudinal Model In contrast to the formalism of the traditional model, political scientists have developed an alternative theory of Supreme Court (and other judicial) decision making: the attitudinal model. …