This book explores how Europe can resolve its foreign fighter conundrum without losing its credibility as a guardian of the rule of law and human rights. Centring on European foreign fighters who travelled to the armed conflict in Syria and Iraq, this book examines to which extent legal responses to the security threat posed by foreign fighters have been consistent with the rule of law and human rights.

The transnational nature of the foreign fighter phenomenon has created a messy labyrinth of legal obligations at the international, European, and domestic levels. To dissect this multi-layered counter-terrorism architecture, the book analyses the intricate interplay between legal norms at these different levels, with a special focus on prosecution and citizenship deprivation. Pertinent issues discussed in this book include multilateral responses by the United Nations, the European Union, and the Council of Europe, as well as the interplay between the 'foreign terrorist fighter' concept and definitions of terrorism. The book also addresses the conflation between counter-terrorism law and international humanitarian law, and the increasing preventive shift within counter-terrorism law. 

Drawing on insights from various fields of law, the book's comprehensive and thorough assessment of the rule of law and human rights implications of permanent international, regional, and domestic legal measures to foreign fighters offers best practices for managing future terrorist threats and challenges. It is an essential resource for both researchers and practitioners in the field of counter-terrorism, national and international security, and international law.

Tarik Gherbaoui is a Researcher in international law in the Research Department of the T.M.C. Asser Instituut in The Hague, the Netherlands.