1 On the more general notion of extra-territoriality of EU Law, see eg, J Scott, ‘Extraterritoriality and Territorial Extension in EU Law’ (2014) 62 American Journal of Comparative Law 1, 87; J Scott, ‘Te New EU “Extraterritoriality”’ (2014) 51 Common Market Law Review 5, 1343. 2 Further, see eg, R Petrov, Exporting the Acquis Communautaire through European Union External Agreements (Baden-Baden, Nomos, 2011). 3 See the seminal decision Case 6/64 Costa v ENEL ECLI:EU:C:1964:66 and, more recently, Case C-402/05 Kadi and Al Barakaat International Foundation ECLI:EU:C:2008:461. Further on the principle of autonomy, see M Klammert, ‘Te Autonomy of the EU (and of EU Law): Trough the Kaleidoscope’ (2017) 42 European Law Review 6, 815; B de Witte, ‘A Selfsh Court? Te Court of Justice and the Design of International Dispute Settlement beyond the European Union ’ in M Cremona and A Ties (eds), Te European Court of Justice and External Relations Law: Constitutional Challenges (Oxford, Hart Publishing, 2014) 33; D Kochenov, ‘EU Law without the Rule of Law: Is the Veneration of Autonomy Worth It?’ (2015) 34 Yearbook of European Law 74; N Nic Shuibhne, ‘What is the Autonomy of EU Law and Why Does that Matter?’ (2018) Nordic Journal of International Law (forthcoming). 9 EU Enlargement, Extra-Territorial Application of EU Law and the International Dimension CHRISTOPHE HILLION AND VINCENT DELHOMME I. Introduction Te EU enlargement policy entails several forms of ‘extra-territorial application’ of EU law – understood here as the application of EU norms beyond the Union’s territory 1 – involving distinct interplays between Union law and international law. Tus the acquis which candidates for membership must adopt and apply prior to their integration into the Union’s legal order does not only comprise EU law stricto sensu¸ it also includes several norms of international law whose compliance the EU requires prior to accession. 2 Te specifc combination of EU and international norms that the Union thereby projects in the pre-accession context, contrasts with the way in which EU and international norms traditionally interact in EU law, given the entrenched principle of autonomy of the EU legal order. 3 In efect, the EU enlargement policy is deeply embedded in, and potentially contributes to strengthening substantive international law.