Attitudes, political strategies and legal constraints affect the decisions that judges make. For long the literature on judicial politics assessed which of these three factors best explain judicial decision-making. This paper takes a different perspective and focuses on two main questions. First, under what conditions are courts more susceptible to the attitudes of their judges, their strategic environment or legal concerns? Rather than focusing on what explains judicial decisions, it focuses on when different factors matter most. Second, are attitudes, strategies or legal precedent more prominent in different systems of judicial review? Regarding my first question, I argue that judicial precedent matters to the extent that the reputation of the court as a judicial institution is at stake. Courts are institutions with specific procedures and raison d’être, which require judges to use precedent and justify departures from it in order to protect their reputation. The judges’ preferences come into play when precedent is non-existing, ambiguous, or when different case law can be applied to support opposite rulings. When the court’s status and legitimacy depend on its support to other political branches, majorities or public opinion, rather than on the consistency of its rulings, strategic considerations may apply. The age of the court and access to judicial review explain whether courts are more open to attitudinal filtrations or bound by legal considerations. Where appointments are rather political and cases are where cases are more visible, strategic considerations will prevail. This logic explains why European systems tend to be constrained by jurisprudence, while attitudinal factors are more salient in the American model. Both systems are equally prone to strategic behaviors. I test my findings by analyzing patterns of judicial decision making on federalism in the US Supreme Court from 1953 to 2007 and in the Spanish Constitutional Court from 1980 to 2008.
