The Army and the Marine Corps just released its newest publication, The Commander’s Handbook on the Law of Land Warfare (Army Field Manual (FM) 6-27/Marine Corps Tactical Publication (MCTP) 11-10C) [hereinafter FM 6-27]. Over 20 years in making, it replaces the widely recognized FM 27-10, The Law of Land Warfare, published in 1956. FM 6-27 provides operational and legal practitioners of the Army and Marine Corps an invaluable tool to help guide land forces in conducting disciplined military operations in accordance with the Law of Armed Conflict (LOAC).

FM 6-27 is an important resource that will assist in developing other doctrine, tactical practices, and training in a manner easily understood by individual Soldiers and Marines. That clarity will contribute to increased and more timely compliance with LOAC, the part of international law that regulates the conduct of hostilities and the protection of war victims.

Specifically, FM 6-27 provides guidance to Soldiers and Marines on the doctrine and practice related to customary and treaty law applicable to the conduct of warfare on land and to relationships between opposing belligerents, in order to train and prepare for combat operations. The principal audience for FM 6-27 is Army and Marine Corps commanders as well as Army and Marine Corps judge advocates. Commanders and staffs of Army and Marine Corps headquarters serving as joint task force or multinational headquarters will still need to refer to applicable joint or multinational doctrine. FM 6-27 is an official publication of the U.S. Army and a referenced publication for the U.S. Marine Corps, and is tailored to land forces. Thus, it does not necessarily reflect the views of, nor does it apply to, the U.S. Navy, U.S. Air Force, or the Department of Defense (DOD) as a whole.

While FM 6-27 is designed to be a useful tool for its intended audience, the Department of Defense Law of War Manual (June 2015, updated December 2016) remains the authoritative statement on the law of war for the Department of Defense (see DOD Directive 2311.01E, DOD Law of War Program). FM 6-27 is not intended to replace or compete with the DOD Law of War Manual, although the topics addressed in FM 6-27 are also addressed in the Manual. In the event of a conflict or discrepancy regarding the legal standards in FM 6-27 and the DOD Law of War Manual, the latter takes precedence. If an apparent conflict or discrepancy is found, it is likely due to FM 6-27’s efforts to provide clear and concise guidance to Commanders and legal practitioners by describing legal concepts more generally rather than exhaustively as found the DOD Law of War Manual.

Where FM 27-10 often merely restated a rule from the Geneva Conventions, FM 6-27 provides explanation and guidance of the various rules and principles. FM 6-27 does this by drawing from treaties to which the United States is a party, customary international law, the DOD Law of War Manual, and other references describing long-standing U.S. military practice. It also draws from the first comprehensive U.S. military regulation of LOAC, prepared by Professor Francis Lieber, and approved by President Lincoln in April 1863 in General Orders Number 100. Similar to the way Francis Lieber outlined the basic LOAC principles as he saw them at the time, the basic LOAC rules and principles applicable to Soldiers and Marines today can be summarized by the following basic Soldier’s Rules (see AR 350-1)/Marine Corps Basic Principles (see MCO 3300.4A), developed by Army and Marine judge advocates to train Soldiers and Marines to conform to LOAC standards applicable in all military operations:

  • Fight only enemy combatants.
  • Do not harm enemies who surrender. Disarm the enemy and turn them over to your superiors.
  • Do not kill or torture enemy prisoners of war or other detainees.
  • Collect and care for the wounded, whether friend or foe.
  • Do not attack medical personnel, facilities, or equipment.
  • Destroy no more than the mission requires.
  • Treat all civilians humanely.
  • Do not steal. Respect private property and possessions.
  • Do your best to prevent violations of the law of war.
  • Report all violations of the law of war to your superiors.

FM 6-27 provides more detailed guidance than what is provided for in the Soldier’s Rules/Basic Principles, but it does not go into the extensive detail of the DOD Law of War Manual.

FM 6-27 follows the general format of the now superseded FM 27-10 and consists of eight chapters: (1) Basic Principles of LOAC; (2) Conduct of Hostilities; (3) Prisoners of War and Other Detainees; (4) Sick and Wounded; (5) Civilians; (6) Occupation; (7) Non-hostile Relations Between Belligerents; and (8) War Crimes and Enforcement of LOAC.

For ready and easy reference during training and operations where internet access may not be available, FM 6-27 will be published in hard copy, in addition to being available online. As noted above, FM 6-27 is a project that has spanned over 20 years. As such, it involved the efforts of many dedicated judge advocates, Soldiers, Marines, and civilian employees. Though their names will not be found anywhere in FM 6-27, this project would never have been successfully completed without their significant contributions.

Note: This article is written in the author’s personal capacity and does not necessarily reflect the views of the United States Army or Department of Defense. At the time of writing, Meier served as the senior civilian adviser to the Army Judge Advocate General on matters related to the Law of Armed Conflict.

IMAGE: KABUL, AFGHANISTAN: American Army members deployed for Mission Resolute Support take part in an end of tour medal ceremony at RS Headquarters on September 4, 2017 in Kabul, Afghanistan. (Photo by Andrew Renneisen/Getty Images)