This book explores legal dilemmas facing detention management during military missions overseas. Armed forces increasingly find themselves facing non-international armed conflict with non-state actors, such as insurgents, terrorists or other civilians, whom they might be permitted to kill or capture in some circumstances. The book considers the legal powers of military forces to apprehend non-State actors and to hold them in ongoing detention or to transfer them to judicial authorities for prosecution. It deals with both theoretical approaches and practical case studies concerning management and treatment of detainees. It concludes by synthesizing the options and delivering a detailed set of guidelines that are proposed as emerging norms for the detention of non-state actors in an armed conflict.