The multiplication of international courts and tribunals in recent decades has paved the way for a judicialisation of international law and has therefore profoundly changed the landscape of international law. Whereas the existence of a panoply of dispute resolution avenues is a welcome development which may be conceptualised as part of an ongoing constitutionalisation of international law, it has concomitantly activated the problem of conflict between different judicial actors. Although doubtlessly designed as an international court sui generis, the ECJ forms part of this international dispute settlement architecture and has to compete with other international actors in the case of jurisdictional overlaps. The recent MOX plant saga is an illustration of these competing forces at play and underscores the self-perception of the ECJ as a constitutional court reluctant to pay deference to the pronouncements of other international judicial actors. Although fitting squarely with the Court’s mandate issued by the framers of the EC Treaty in Article 292, this approach risks an undesirable fragmentation of international law as a whole, which could be avoided by reference to a number of conflict avoidance devices available to international courts and tribunals.