Machine generated contents note: Introduction; Part I. International Law and the EU Constitution - Normative Aspects: 1. On 'federal ground': the European Union as an (inter)national phenomenon; 2. On 'middle ground': the European Union and public international law; 3. The 'succession doctrine' and the European Union; 4. European law and member state agreements: an ambivalent relationship?; Part II. Foreign Affairs and the EU Constitution - Vertical Aspects: 5. Federalism and foreign affairs: mixity as an (inter)national phenomenon; 6. Dual federalism constitutionalised: the emergence of exclusive competences; 7. Parallel external powers: from 'Cubist' perspectives towards 'naturalist' constitutional principles?; 8. The ERTA Doctrine and cooperative federalism; Part III. Foreign Affairs and the EU Constitution - Horizontal Aspects: 9. External Union powers: competences and procedures; 10. External Union legislation: international agreements; 11. The 'treaty power' and parliamentary democracy: comparative perspectives; 12. External Union policies: a substantive overview; Annex. Foreign affairs provisions in the EU Constitution (selection).