The following information was obtained from the 2012 Officer Candidates School Student Outline.


1. Without the aid of references, describe the Law of War without omitting key components. (MCCS-UCMJ-1003)


1. Without the aid of references, define the purpose of the Laws of War without omission. (MCCS-UCMJ-1003a)
2. Without the aid of references, describe actions towards enemy personnel directed by the Laws of War without omission. (MCCS-UCMJ-1003b)
3. Without the aid of references, describe actions towards enemy property and facilities directed by the Laws of War without omission. (MCCS-UCMJ-1003c)


a. Law of War: That part of international law that regulates the conduct of armed hostilities. It is often called the law of armed conflict. The law of war encompasses all international law for the conduct of hostilities binding on the United States or its individual citizens, including treaties and international agreements to which the United States is a party, and applicable customary international law.

b. Sources of the Law of War. The law of war is derived from two principal sources:

(1) Lawmaking Treaties (or Conventions), such as the Hague and Geneva Conventions.(2) Custom. Although some of the law of war has not been incorporated in any treaty or convention to which the United States is a party, this body of unwritten or customary law is firmly established by the custom of nations and well defined by recognized authorities on international law.

(3) Lawmaking treaties may be compared with legislative enactments in the national law of the United States and customary law of war with the unwritten Anglo-American common law. Common law is a system of juriprudence in which binding law is based solely on previous decisions and customs as distinct from statute law created by the legislature.

c. Nine Principles of the Law of War provided in the Geneva Convention:

(1) Fight only enemy combatants.(2) Do not harm enemies who surrender, disarm them and turn them over to your superior.

(3) Do not kill or torture prisoners.

(4) Collect and care for the wounded, whether friend or foe.

(5) Do not attack medical personnel, facilities, or equipment.

(6) Destroy no more than the mission requires.

(7) Treat all civilians humanely.

(8) Do not steal; respect private property and possessions.

(9) Do your best to prevent violations of the law of war; report all violations to your superior, a military lawyer, a chaplain, or provost marshall.


The conduct of armed hostilities on land is regulated by the law of land warfare and it is inspired by the desire to diminish the evils of war by:

a. Protecting both combatants and noncombatants from unnecessary suffering.

b. Safeguarding certain fundamental human rights of persons who fall into the hands of their enemy, particularly prisoners of war, the wounded and sick, and civilians. Following the law of war encourages reciprocal conduct by the other side.

c. Facilitating the restoration of peace. Wartime attrocities make it difficult for opposing sides to reconcile after conclusion of hostilities. Additionally, destroying no more than required to accomplish the mission reduces waste and cost of reconstruction.

d. Helping accomplish the mission. Following the law of war decreases enemy resistance and makes them more willing to surrender. Additionally, following the law of war increases broad public support for our mission, especially important during counter-insurgency operations.

e. Promotes internal unit discipline. Following the law helps maintain clarity of purpose in the chaotic combat environment. When warfighters know they will be held accountable for their actions, it is more likely that they will execute their mission in accordance with the laws of war.


a. Engage only Hostile Forces and Combatants. A Hostile Force is any civilian, paramilitary, or military force or terrorists, with or without national designation, that has committed a hostile act, exhibited hostile intent, or has been declared hostile by appropriate U.S. authority. Hostile forces may also be called Enemy Combatants. The Geneva Convention provides the following categories of persons that may be treated as Combatants:

(1) Members of the armed forces of parties to the conflict.(2) Members of militias and organized resistance movements belonging to a Party to the conflict.

(3) Members of regular armed forces belonging to governments not recognized by the Detaining Power.

(4) Inhabitants of non-occupied territory who spontaneously take up arms to resist invading forces.

b. Do not engage Non-Combatants. Non-Combatants are civilians not engaged in combat.

c. Follow the Rules of Engagement (ROE). ROE are the primary tools for regulating the use of force. ROE provides guidance from the President and Secretary of Defense (SECDEF), as well as subordinate commanders, to deployed units on the use of force.

(1) ROE are defined as directives issued by competent military authority that delineate the circumstances and limitations under which U.S. forces will initiate and/or continue combat engagement with other forces encountered.(2) Legal factors provide the foundation for ROE, including customary and treaty law principles regarding the right of self-defense and the laws of war. Non-legal issues, such as political objectives and military mission limitations are also essential to the construction and application of ROE. Judge Advocates play an important role drafting ROE. however ROE are ultimately the commander’s rules that must be implemented by those who execute the mission.

d. Offensive versus Defensive ROE. There are two distinct types of ROE, offensive ROE and defensive ROE. Each provide very different rules for when you may engage enemy forces.

(1) Offensive ROE. Offensive ROE apply only during the offensive phase of an operation or military campaign. When applying offensive ROE, you will engage enemy forces based primarily upon their status as a Declared Hostile Force.

(a) Declared Hostile Force (DHF): any civilian, paramilitary, or military force, or terrorist that has been declared hostile by appropriate U.S. authority.(b) Once a force is declared to be “hostile,” U.S. units may engage it without observing a hostile act or demonstration of hostile intent; i.e., the basis for engagement shifts from conduct to status. Once a force or individual is identified as a DHF, the force or individual may be engaged, unless surrendering or hors de combat due to sickness or wounds.

(2) Defensive ROE. In order to engage enemy forces under defensive ROE, the enemy must first display a hostile act or hostile intent. You must have positive identification of the enemy combatant, assess possible collateral damage, and apply proportional force.

(a) Under defensive ROE, you cannot engage an enemy combatant until they display present hostile intent or commit a hostile act. The fact that they are a known member of a hostile enemy force alone is not sufficient to target and engage them on sight. They may be captured on sight to remove them from the fight, but using the minimum force necessary. The intent under defensive ROE is to accomplish the mission with the minimum casualties possible on both sides. Defensive ROE is based on the inherent right of self defense. Some examples of when defensive ROE is used are peacekeeping, counter-insurgency, and nation building missions.(b) Hostile Act (HA): an attack or other use of force against the United States, U.S. forces, or other designated persons or property. It also includes force used directly to preclude or impede the mission and/or duties of U.S. forces, including the recovery of U.S. personnel or vital U.S. government property. It is an attack or any other use of force against U.S. forces, property, or designated persons. Some examples are firing small arms or detonating an improvised explosive device.

(c) Hostile Intent (HI): the threat of imminent use of force against the United States, U.S. forces, or other designated persons or property. It also includes the threat of force to preclude or impede the mission and/or duties of U.S. forces, including the recovery of U.S. personnel or vital U.S. government property.

(d) HA is the threat of the imminent (not necessarily immediate) use of force against U.S. forces, property or designated persons. Determining that an activity constitutes hostile intent requires judgment and knowledge of enemy tactics. Determining if something is a threat requires quick, but sound decision making process. Some examples of possible hostile intent are an individual burying a suspicious cylinder along a road (likely improvised explosive device), an unknown armed group massing in your area of operation, an unknown vehicle speeding to catch up with your convoy, or an unknown armed individual on a rooftop position along a route used by U.S. forces. Further observation and information sometimes confirms the percieved hostile intent. At other times the suspicious activity may not to be hostile intent at all. For example, the individual digging along a road may just be repairing a drainage pipe, not planting an IED. Tactical patience and sound judgment help ensure that when we do engage targets, that the shooting is justified.

(e) Positive Identification (PID): A reasonable certainty that your target is a legitimate military target. PID does not require 100% certainty. You must have clear line of sight to target and know what is behind it.

(f) Proportional Force: Nature, duration, and scope of force necessary to defeat a perticular threat. Do not use excessive force that will destroy more than required to accomplish the mission. Proportionality is the use of force in self-defense. It should be sufficient to respond decisively to hostile acts or demonstrations of hostile intent. Such use of force may exceed the means and intensity of the hostile act or hostile intent, but the nature, duration and scope of force used should not exceed what is required. The concept of proportionality in self-defense should not be confused with attempts to minimize collateral damage during offensive operations.

(g) Escalation of Force (EOF). One of the most important topics related to ROE is the concept of Escalations of Force (EOF). EOF has been developed and emphasized during recent operations, most notably in Iraq and Afghanistan. EOF can take several different forms. On one level, EOF is simply the modem variant of what used to be called “graduated force measures.” When time and circumstances permit, you should attempt to use lesser means of force. Begin by applying the minimum use of force possible, and increase level of force up to use of deadly force if required.

e. Obligations towards Protected Persons and Non-Combatants. In the combat environment you are obligated to prevent harm of certain categories of individuals.

(1) Protected Persons:

(a) Medical and religious personnel.(b) Relief society workers, NGOs, Red Cross.

(c) Foreign diplomats and embassy personnel.

(2) Non-combatants. It is important to understand when a combatant’s status changes to non-combatant. Combatants become non-combatants when taken out of the fight and no longer actively engaged in fighting. These include enemy in any of the following categories:

(a) Surrendered.(b) Injured or incapacitated.

(c) Captured Enemy Prisoners of War (EPWs).

f. Obligations towards property and facilities. You will never destroy more property than is required to accomplish the mission? Some categories of property are provided special consideration and protected from attack:

(1) Red Cross/Red Crescent property.(2) Religious Sites.

(3) Historical Sites.

(4) The special protections afforded to these categories of property are not absolute and may be lost if used by Combatants

1. The Law of Land Warfare – MCRP 5-12.1A/FM 27-10
2. DoD Law of War Program – DoD Directive 5100.77, 1998
3. Treaties Governing Land Warfare – Army Pamphlet 27-1
4. Protocols to the Geneva Conventions – Army Pamphlet 27-1-1
5. DoD Dictionary of Military and Associate Terms – Joint Pub 1-02
6. Operational Law Handbook – The Judge Advocate General’s Legal Center and School
7. Law of War Deskbook – The Judge Advocate General’s Legal Center and School