The first edition of this seminal textbook made a significant impact on the teaching of EU external relations law. This third edition continues to be the leading text in the field. It retains its hallmark dual perspective, looking at questions from an EU constitutional law perspective (the principles, powers, and the role of the institutions); and an international law perspective (the effects of international law within the EU, and the position of the EU in international organisations such as the WTO). It continues to explore key policy areas such as trade, security and defence, police and judicial cooperation, the environment, and human rights, drawing on the expertise of leading scholars in these fields. The book's 'text, cases, and materials' approach provides students with a one-stop shop resource, allowing them to gain a thorough understanding of how the law has developed in this area, its judicial interpretation, and scholarly appraisal. Each chapter concludes with a section entitled 'The Broader Picture of EU External Relations Law', which weaves together the diverse and complex materials into a coherent whole and stimulates critical discussion of the topics covered. The fully revised third edition captures a wide range of new legislative instruments, international agreements, case law, and practice of EU external action developed over the past half decade in response to a geopolitically more challenging environment. Alongside the editors, contributors include Anne Thies, Andrea Ott, Jed Odermatt, Morten Broberg, Laurent Pech, Joelle Grogan, Gracia Marín Durán, and Claudio Matera. For this third edition, new contributors, including Marisa Cremona, Tamás Molnár, and Viktor Szép, provide additional expertise and fresh perspectives. The text has benefitted from the participation of student assistants who have advised on writing style and approach, ensuring ease of use and comprehension.