The Causes of Personalism on Apex Courts: Legal Systems, Incentives, and Personalism Beyond the Courts

Despite existing scholarship on judicial behavior, institutional design, and the political role of courts, surprisingly little research has examined political personalism on apex courts. Research on political personalism has mainly focused on how it presents itself in the executive and legislative branches, with little research on its manifestation on apex courts. In a previous article, I developed a novel conceptualization and original measure of personalism on apex courts. That study demonstrated a cross-country variation in levels of personalism across apex courts. The present article builds directly on that by aiming to explain the sources of this variation and asking: what factors account for differing levels of personalism on apex courts? To answer this question, the article advances and empirically tests three explanatory variables that operate at the legal, institutional, and political levels. First, the article examines legal tradition, distinguishing between common law and civil law systems. I hypothesize that apex courts in common law jurisdictions will exhibit higher levels of personalism than those in civil law systems. This expectation reflects long-standing differences in the conception of the role of the judge and practices on the court, with common law systems traditionally encouraging individual judicial expression and civil law systems emphasizing more collective decision-making and institutional anonymity. Second, the article explores the influence of judicial terms and post-court career opportunities. I hypothesize that courts whose justices serve under fixed term limits, as opposed to life tenure or service until mandatory retirement, will display higher levels of personalism. Where judges anticipate future professional opportunities beyond the bench, they may have stronger incentives to cultivate individual reputation, influence, and prominence while in office. Third, the article situates apex courts within their broader political environments by examining the relationship between personalism on the courts and personalism in the executive and legislative branches. I hypothesize that higher levels of political personalism elsewhere in the system will be associated with greater personalism on apex courts. By identifying the conditions under which personalism emerges and intensifies within apex courts, this article advances scholarship on judicial politics, judicial behavior, and judicial power, offering a clearer explanation of why some courts exhibit higher levels of personalism while others operate in more collegial modes.