During armed conflict, non-State armed groups deprive individuals of their liberty. While this is not a new phenomenon, its pervasiveness is reflected by recent examples in Colombia, Libya, Syria, Ukraine, Mali and the Democratic Republic of the Congo. Yet, examining these activities goes beyond its mere acknowledgment. It involves questions concerning their legality and the non-State armed groups' motivations when depriving individuals of their liberty. Drawing on his personal experiences while working for various humanitarian organizations, Ezequiel Heffes aims at elucidating how international law can be used as a protective tool in relation to individuals placed in detention by non-State armed groups. Based on case studies of selected groups and a normative and doctrinal analysis, he proposes minimum humanitarian principles applicable to those situations. By addressing a contemporary issue that touches upon a number of legal regimes, this study makes a valuable contribution to the law applicable in armed conflict.

'In this sophisticated work by a leading practitioner-scholar of international law and armed non-state actors, Ezequiel Heffes masterfully combines rigorous legal analysis with the considered practice of armed groups. In doing so, he has made a significant contribution to the pressing issue of the legal regulation of detention by non-state armed groups.'

Sandesh Sivakumaran - University of Cambridge

‘This is an essential read for scholars and humanitarian practitioners engaged in efforts to influence the behaviour of NSAGs towards compliance with protection norms in times of armed conflict. Heffes succeeds not only in leading the reader to a better understanding of the way in which the law governs these practices but also in providing important and fascinating insights into how and why armed groups behave in certain ways.’

Katharine Fortin - Utrecht University

‘Through a rich examination of the practice of non-state armed groups and careful analysis of legal developments in international humanitarian and human rights law, Ezequiel Heffes provides valuable insight into the protective role of international law for persons detained by non-state armed groups. Practitioners and academics alike will greatly benefit from this unique combination of legal analysis and real-world practice.’

Nathalie Weizmann - United Nations Office for the Coordination of Humanitarian Affairs

‘Had it been written a few decades back this monograph would have been classified as science fiction. Today, it contributes to a growing body of scholarship that chips away at the positivist international lawyer’s preferred legal fiction: that the state is the only, or even main, legal person. This is an excellent book on how international law is perceived and applied, in actuality and potentiality.’

Ioana Cismas - Centre for Applied Human Rights and York Law School

‘In Detention by Non-State Armed Groups under International Law, Ezequiel Heffes challenges the traditional state-centrism of international law to tackle a practice often overlooked, complex to explain, and challenging to analyse. With a perspective rooted in legal pluralism, supported by extensive interdisciplinary research, and grounded in case studies of several armed groups, Heffes offers a sharp, clear, and compelling analysis that changes our understanding of non-state detention in warzones.’

René Provost - McGill University

‘Ezequiel Heffes takes his readers on a captivating journey: from academic debates to real-world conflicts, from modern interpretations of international humanitarian and human rights law to case studies on how NSAGs detain in practice. Driven by the desire to use the law to protect people, this book provides excellent insights into the reality of detention by NSAGs and how international law applies - or should apply - to that reality.’

Tilman Rodenhäuser - International Committee of the Red Cross