Public support forms the backbone of judicial power. Yet studies of public support for judicial institutions has largely focused on domestic courts, leaving scholars with limited data and theoretical accounts for the public standing of international courts. In this paper we seek to address these limitations of the extant literature by evaluating the extent of the legitimacy enjoyed not only by two of the country’s highest courts, the German Constitutional Court and the Federal Court of Justice, but also the European Union’s highest court, the Court of Justice (CJEU). To do so, we use data from a panel survey fielded in Germany to a nationally-representative sample of approximately 3100 respondents in October 2020. Building on the theoretical and empirical work of Gibson and Caldeira (1995, 1998), we first examine the political and socioeconomic determinants of support for each of these judicial institutions. The political factors we consider include ideology, partisanship, support for European integration, and support for democratic norms. As for socioeconomic variables, among others we examine respondents’ income, age, and whether a respondent was a resident in the former East Germany. We then turn to comparing these levels of support to identify the characteristics of individuals who support domestic German courts to a greater extent than they support the CJEU. Our findings provide insight into the extent to which domestic courts can extend legitimacy to the CJEU and serve as a conduit for the expansion of the scope of European Union law.