Crucial and Routine Decisions: A New Explanation of Why Ideology Affects U.S. Supreme Court Decision Making the Way It Does

This Article is an attempt to show why the effect of ideological preferences in models of the Supreme Court's decisions works the way it does. First, I present an analysis of the expectations justices can form about the results of their decisions. Next, I suggest that for many kinds of cases the conditions for rational choice cannot be met consistently and that, as a consequence, justices use their policy preferences to reach decisions. I argue that the differential effect of attitudinal indicators in empirical studies turns on the type of decisions that are made in particular classes of Supreme Court cases. I then present an examination of Court decisions that supports this assertion. I conclude by discussing ramifications these ideas have for studies of Supreme Court decision making.