A theory of external judicial politics: the ECJ as cautious gatekeeper in external relations

Abstract Scholars have extensively studied how the European Court of Justice (ECJ) interacts with Member State courts. The ECJ’s behaviour vis-à-vis international tribunals remains, however, underexplored despite its salience for EU global actorness. The ECJ does at times condone and at other times reject cooperation with international tribunals in that it either authorises or prohibits EU and Member State participation in relevant regimes. What drives ECJ behaviour? While intuitive, European law fails to fully account for it. This study draws on models of bounded discretion to explain ECJ behaviour in external judicial politics. It argues that two factors – namely jurisdictional overlap between the European legal order and international tribunals as well as the centrality of these tribunals in global governance – decisively influence the preferences of the ECJ, Member States, the European Commission and Parliament and thus delimit the range of politically viable rulings and shape ECJ behaviour.