This Article argues that the cooperation obligations of the Member States under EU law are best understood as forming part of an overall duty of EU loyalty and elaborates on the consequences of framing it in this way. EU loyalty legally requires Member States to make the common EU interest their own. The Article further demonstrates that EU loyalty is more relevant and more stringently applied in EU external relations than within the EU legal order. Loyalty obligations of the Member States reach into the future, extend to hypothetical situations, and are at a comparatively high level of abstraction aimed to protect the Union's ability to act effectively on the international plane. This limits Member States’ margin of manoeuvre, including when they take unilateral external action within the realm of their retained national competences. The Article explains that this may be functionally justified by the high stakes of non-concerted external action. However, and in particular with the EU's increased external powers and the ever-growing relevance of international cooperation, the stringent application of cooperation requirements should be (better) explicated and justified.

The EU legal system, with its many hands and complex architecture, in which national and European powers are closely interwoven, requires a particular form of cooperation. This delicately developed cooperation may be influenced by the EU's ambition to take a statelike role in international relations. Indeed, the basic assumption underlying this Article is that it is not only the EU's complexity that influences the EU's external actions—usually seen as limiting the EU's capacity to speak with one voice—but also that the EU's external actions influence its internal set-up and cooperation practices. As a result of the EU's participation in international legal regimes, established organizational principles might come under pressure. Furthermore, within the complexity of the European legal order, the potential consequences could be more disturbing for stability than within the—monolithic, in comparison—structure of states.

Counter-terrorist sanctions against private individuals adopted by the EU and by the UN are an exceptionally illustrative example of the executive’s power grasp, where the dangers of counter-terrorist policies and of externalized rulemaking have mutually reinforced each other. This article (re-)considers the role of the judiciary in the face of extreme exercise of externalized executive powers, demonstrates that multilayered governance has extended the powers of courts, shows that the justified exercise of judicial power has led the EU institutions and the Member States into a self-inflicted catch-22, and makes an argument that the extended powers of the executive and of the judiciary should be contained and guided by a principled choice of the constituent power. Constitutional law should require the judiciary to take a substantive approach to multilayered governance that reflects the principle of separation of powers.

Counterterrorist sanctions against individuals are a prime example of pluralism. Multiple claims of constitutional authority (in resolutions of the UN Security Council, under European Union law, and national law) assume to govern the same legal situation. Choosing between these different authorities has great implications for the legal situation of individuals. This paper analyses the legal position of individuals facing this plurality of claims of constitutional authority and how their rights are largely dependent on the choices of domestic courts. Attention will be given not only to procedural and judicial rights but also to the broader implications of individual sanctions as an example of pluralism. What does it mean for popular sovereignty? Do patterns or guidelines emerge of how courts should address multiple claims of authority? The paper takes into account the latest amendments of the UN sanctioning procedure (Resolutions 1988 and 1989 (2011)).

Rulings in the cases of OMPI, Sison and Segi – Violation of the right to a fair hearing, the duty to give reasons, and the right to judicial protection – Jurisdiction to review lists of terrorist suspects – Extension of Article 35 TEU – Preliminary rulings on common positions – Improvements of the listing procedure – New legal bases for restrictive measures under the Treaty of Lisbon – Recommendations how to reform the autonomous EU listing procedure further