Institutional Design and Attitudinal Expectations: Linking Models of Judicial Appointments to Voting Expectations on National Apex Courts

Theories of institutional design suggest that the selection mechanism for judges on apex courts is directly related to both the ideological disposition of appointed judges and their subsequent decision-making on the bench. The more partisan actors involved in the selection process, the greater the ideological and partisan correspondence between selectors and successfully appointed judges. The impacts of partisan involvement in judicial selection on the ideological and partisan nature of judges have been studied extensively in the United States, where research consistently shows that the President and legislature appoint Supreme Court justices who reflect their own ideological leanings. Yet, while the veracity of apex judges as policy maximizers has been demonstrated in numerous democracies outside the US very little theoretical or empirical work has been done on the link between selection model and judicial voting behaviour. This is surprising given that contemporary studies of judicial voting behaviour suggest that there is significant variation in the ideological propensities of judges on non-US apex courts, even between countries with similar methods of appointment. But why, in some democracies, do judges exhibit ideological behaviour, and not elsewhere? This paper argues that the disparity in findings of ideological voting behaviour on apex courts is largely a consequence of comparative research on judicial selection failing to comprehensively account for the political context of the judicial nomination process. To that end, we propose a novel theory that accounts for the relationship between model of appointment of judges to national apex courts, the expected ideological position of any given nominee, and the implications for subsequent judicial voting behaviour once the nominee is on the court. Further, building on the appointments and confirmation models of judicial selection in American politics, we develop and generalizable framework for conducting single case research on judicial selection processes and their effects in a comparative perspective. Ultimately, we argue that any attempt to connect the model of appointment to judicial behaviour requires a nuanced examination of the political context of each nominator’s choice in the nomination process. We demonstrate the power of our approach by using original data on the appointment of justices to the High Court of Australia, as well as an original dataset of voting behaviour on the Court. This study enriches a growing body of comparative judicial politics and provides a foundational mechanism by which to compare the impact of ideology on judicial behaviour across multiple countries’ apex courts.