This United States Army National Security Department Judge Advocate General Legal Center and School deskbook, 2020 Edition US Army Law of Armed Conflict Documentary Supplement, provides students and practitioners with a ready reference of collected materials relevant to the study and practice of national security law. Modifications are based on the curriculum at The Judge Advocate General's Legal Center and School, with a focus on plenary instruction provided to students in both basic and graduate courses, as well as more specialized instruction during electives and short courses. However, this volume has historically found its way to the field, informing the practice of judge advocates in both garrison and combat. The 2020 edition adds the U.S. Constitution, the Optional Protocol to the Convention on the Rights of the Child, the Declaration on Principles of International Law Friendly Relations and Co-Operation Among States in Accordance with the Charter of the United Nations, the Convention on the Non-Applicability of Statutory Limitations to War Crimes and Crimes Against Humanity, and the 2020 Department of Defense Policy on Landmines. The 2020 edition removes the 2011 Fact Sheet: New Actions On Guantánamo and Detainee Policy.