In Interaction and Delimitation of International Legal Orders, the author describes how actions of international dispute settlement bodies set up within institutionalized treaty regimes contribute to the establishment of autonomous international legal orders. Based on examples from the WTO, the EU, the law of the sea and international environmental law, the book presents a typology of uses of legal norms and principles that are extrinsic in the sense that they derive not from the regime, but from general public international law, other treaty regimes, or the jurisprudence from courts operating in other fields. The investigation contradicts assertions that international courts will contribute to systemic integration and offers reflections on repercussions for the legitimacy of international norms and institutions.