The interaction between military and civilian courts, the political power that legal prerogatives can provide to the armed forces, and the difficult process civilian politicians face in reforming military justice remain glaringly under-examined, despite their implications for the quality and survival of democracy. This book breaks new ground by providing a theoretically rich, global examination of the operation and reform of military courts in democratic countries. Drawing on a newly created dataset of 120 countries over more than two centuries, it presents the first comprehensive picture of the evolution of military justice across states and over time. Combined with qualitative historical case studies of Colombia, Portugal, Indonesia, Fiji, Brazil, Pakistan, and the United States, the book presents a new framework for understanding how civilian actors are able to gain or lose legal control of the armed forces. The book's findings have important lessons for scholars and policymakers working in the fields of democracy, civil-military relations, human rights, and the rule of law.