This book reappraises the constitutional fundamentals of EU foreign relations law. The essays in the book examine and reassess the basic principles of EU foreign relations law that have emerged over 50 years of incremental Treaty-based and judicial development and explore the particular character of the EU's "external constitution". They have been written against a background of change and debate: the deliberation over the character of the appropriate constitutional framework which has surrounded the drafting of the Constitutional and Reform Treaties, the increasingly cross-pillar nature of much EU external action, and renewed interest in the accountability of foreign relations policy and practice to democratic and judicial review within and without the EU.