This book explores how States and armed groups deprive us of liberty in armed conflict. Intriguing insights into original field records of internal laws and first-hand testimonies by fighters and humanitarians reveal hidden patterns of belligerents’ controversial behaviours in relation to three complex aspects of security detention in non-international armed conflict that remain unsettled in international law – permissible grounds, procedural guarantees, and transfer standards. As you flip through the pages of this fascinating book, you will gain a new understanding of where the boundary of unlawful confinement lies between local and international law and why we need a new international legal framework to protect us from arbitrariness in the warring parties’ decision to detain.