The separation of powers and the Supreme Court: A new institutional analysis of inter-branch disputes, 1946--2005

Very few theories of Supreme Court decision making offer explanations of the Court's opinions in separation of powers cases. My study attempts to address this omission in the literature by using separation of powers cases to test the explanatory and predictive power of four different approaches to Supreme Court decision making: the attitudinal model, the "strategic" approach, ruling-coalition theory, and historical new institutionalism. The study hypothesizes that historical new institutionalist approaches are in the best position to explain the outcomes in these cases.; As a test of this hypothesis, I am analyzing all significant separation of powers cases decided by the Vinson, Warren, Burger and Rehnquist Courts. Attitudinal models fail to explain why justices of widely different ideological preferences vote along the same lines in these cases. The strategic model would predict that the justices would support those institutions that are controlled by people with attitudes that are most closely aligned with the Court majority, but this turns out not to be the case. The theory of ruling coalitions suggests that the Court's decisions will reflect the preferences of dominant ruling coalitions, but the data suggests either that this is not consistently true or that separation-of-powers cases fall outside the scope of the model because they reflect divisions among dominant coalitions.; Instead, the preliminary results demonstrate that the justices' behavior is most consistent with that which we would expect from an historical new institutionalist analysis. There is evidence that justices form endogenous preferences based on the structure of constitutional doctrine, and that these preferences are not reducible to the sort of conventional policy preferences measured by attitudinalists. Moreover, in these cases the justices also appear to be pursuing a distinctive institutional mission related to the maintenance of judicial power and a system of checks and balances; the outcomes in these cases do not suggest that the justices are stealthily promoting conventional policy preferences. I will examine the question of whether separation of powers cases expose limits to prevailing models of judicial behavior, and also the question of what new institutionalist analysis can contribute to our understanding of Supreme Court politics.