17.2 The Law of War
Key Takeaways
- The five law of war principles are military necessity, humanity, distinction, proportionality, and honor.
- Military necessity never authorizes actions specifically prohibited by the law of war, such as murder or ill treatment of prisoners of war or the taking of hostages.
- Employment of voluntary or involuntary human shields is a fundamental violation of the principle of distinction.
- Airmen who parachute from a disabled aircraft and offer no resistance may not be attacked.
- Each service member has a duty to comply with the law of war, including the refusal to comply with clearly illegal orders to commit law of war violations.
Definition and Purpose
"The law of war, also called the Law of Armed Conflict (LOAC)," is defined by DoD as the treaties and customary international law binding on the United States that regulate: the resort to armed force; the conduct of hostilities and the protection of war victims in international and non-international armed conflict; belligerent occupation; and the relationships between belligerent, neutral, and non-belligerent states.
Purpose. The law of war "arises from civilized nations' humanitarian desire to lessen the effects of conflicts." It:
- Protects combatants and noncombatants, including civilians, from unnecessary suffering
- Provides fundamental protections for persons who fall into the hands of the enemy — particularly prisoners of war, civilians, and military wounded, sick, and shipwrecked
- Aims to keep conflicts from degenerating into savagery and brutality, thereby helping restore peace
- Assists commanders in ensuring the disciplined and efficient use of military force and preserving the professionalism and humanity of combatants
That last purpose is the one candidates overlook: the law of war serves military discipline and effectiveness, not only humanitarian ends.
Training. DoDD 2311.01, Department of Defense Law of War Program, requires each military department to ensure law of war observance, prevent violations, ensure prompt reporting of alleged violations, and appropriately train all forces. Training is "an obligation of the United States under provisions of the 1949 Geneva Conventions, other law of war treaties, and customary international law." Personnel receive training commensurate with their duties, and aircrews, medical personnel, and security forces receive specialized training.
Treaty status. Article six of the U.S. Constitution states that treaty obligations are "the supreme law of the land," and the Supreme Court has held that international legal obligations, including custom, are part of U.S. law. Treaties therefore enjoy equal status to laws passed by Congress and signed by the President, binding military personnel, civilians, and contractors authorized to accompany the Armed Forces.
The Five Principles
| Principle | AFH 1's definition | The limit |
|---|---|---|
| Military Necessity | Justifies the use of all measures needed to defeat the enemy as quickly and efficiently as possible, that are not prohibited by the law of war. Attacks must be limited to military objectives | "Military necessity does not authorize all military action and destruction." It may never authorize prohibited acts such as murder of prisoners of war, ill treatment of prisoners or internees, taking of hostages, or reprisal against a protected person or object |
| Humanity | Forbids the infliction of suffering, injury, or destruction unnecessary to accomplish a legitimate military purpose | "Once a military purpose has been achieved, inflicting more suffering is unnecessary and must be avoided." An enemy combatant placed hors de combat — taken out of the fight by being severely wounded or captured — serves no military purpose by continued attack |
| Distinction | Imposes a requirement to distinguish between military forces and the civilian population, and between unprotected and protected objects. Force may be directed only against military objectives | Civilian objects — places of worship, schools, hospitals, dwellings — are protected, but can lose protected status if used to make an effective contribution to military action. Human shields are a fundamental violation, as is disguising military forces as civilians |
| Proportionality | "The expectation that even where one is justified in acting, one must not act in a way that is unreasonable or excessive." Weighs justification against expected harms | Does not require that no incidental damage result. It creates obligations to refrain from attacks where expected incidental harm would be excessive in relation to the concrete and direct military advantage anticipated, and to take feasible precautions |
| Honor | Requires a certain amount of fairness in offense and defense and a certain mutual respect between opposing military forces; forbids conduct that would constitute a breach of trust with the enemy | Good faith prohibits five things: killing or wounding by perfidy (treachery), misusing certain signs, fighting in the enemy's uniform, feigning non-hostile relations to seek advantage, and compelling nationals of a hostile party to fight against their own country. Honor does not forbid ruses and other lawful deceptions |
Two nuances generate most of the items. First, proportionality does not prohibit all incidental damage — it prohibits excessive damage relative to the anticipated military advantage. Second, honor permits ruses but prohibits perfidy — the line falls at breach of trust, not at deception generally.
Classes of Persons
The Geneva Conventions of 1949 consist of four separate international treaties aiming to protect all persons taking no active part in hostilities, including members of military forces who have laid down their arms and combatants placed out of the fight due to sickness, wounds, detention, or any other cause.
The doubt rule is a reliable item: "Should doubt exist as to whether a captured individual is a lawful combatant, noncombatant, or an unprivileged belligerent, the individual will receive the protections of the Geneva Prisoner of War Convention until their actual status is determined."
| Class | Definition |
|---|---|
| Combatants (lawful or "privileged") | (1) Members of the military forces of a state party to a conflict, aside from certain medical and religious personnel; (2) under certain conditions, members of militia or volunteer corps not part of the state's military forces but belonging to a state; (3) inhabitants of an area participating in a popular uprising against foreign invaders — a levée en masse. A combatant is commanded by a person responsible for subordinates, wears fixed distinctive emblems/uniforms recognizable at a distance, carries arms openly, and conducts operations according to the law of war. Combatants have the right to prisoner of war status and legal immunity from domestic law for acts done under military authority and in accordance with the law of war |
| Noncombatants | Certain military personnel not authorized to engage in combatant activities, such as permanent medical and religious personnel. They must be respected and protected and may not be made the object of attack |
| Civilians | A type of noncombatant; protected persons who may not be made the object of direct attack. They may suffer injury or death incident to a direct attack on a military objective without violating the law of war, if the attack is on a lawful target by lawful means and adheres to proportionality. Civilians who take an active or direct part in hostilities forfeit protection from being made the object of attack |
| Unprivileged belligerents | A term not used in the Geneva Conventions but defined in the DoD Law of War Manual to include "lawful combatants who have forfeited the privileges of combatant status by engaging in spying or sabotage, and private persons who have forfeited one or more of the protections of civilian status by engaging in hostilities" |
The four combatant criteria — responsible command, fixed distinctive emblems recognizable at a distance, arms carried openly, and operations conducted according to the law of war — are a standard four-item recall question.
Military Objectives and Protected Objects
A military objective is "any object which by its nature, location, purpose, or use makes an effective contribution to military action and whose total or partial destruction, capture, or neutralization in the circumstances ruling at the time offers a definite military advantage." Examples: tanks, military aircraft, bases, supplies, lines of communication, and headquarters.
Protected objects include medical units or establishments; transports of wounded and sick personnel; military and civilian hospital ships; safety zones established under the Geneva Conventions; religious, cultural, and charitable buildings; monuments; and prisoner of war camps. If used for military purposes, they may lose their protected status.
Operations short of violence are permitted against civilians when militarily necessary — stopping and searching civilians for weapons, verifying they are civilians, temporarily detaining civilians for mission accomplishment, self-defense, or their own safety, collecting intelligence including interrogating civilians, restricting or directing their movement for protection, and seeking to influence enemy civilians with propaganda. What is prohibited is making civilians the object of attack, using them as shields or hostages, and measures of intimidation or terrorism including acts or threats of violence with the primary purpose of spreading terror.
The good-faith standard for commanders is testable: "Even when information is imperfect or lacking, as will frequently be the case during armed conflict, commanders and other decision-makers may direct and conduct military operations, so long as they make a good faith assessment of the information that is available to them at the time."
Enemy Aircraft and Aircrew
| Situation | Rule |
|---|---|
| Enemy military aircraft | May be attacked and destroyed, unless in neutral airspace or territory |
| Airmen parachuting from a disabled aircraft | May not be attacked if they offer no resistance |
| Airmen who resist in descent, or who are downed behind their own lines and continue to fight | May be subject to attack |
| Enemy public and private nonmilitary aircraft | Generally not subject to attack unless used for a military purpose |
| Civil aircraft that initiates an attack | May be considered an immediate military threat and lawfully attacked. A threat may also exist on reasonable suspicion of hostile intent — approaching a military base at high speed, or entering enemy territory without permission and disregarding signals or warnings |
| Military medical aircraft | Used exclusively for removal of the wounded and sick and transport of medical personnel and equipment; protected while flying at heights, times, and on routes specifically agreed upon between the parties. A medical aircraft in violation of established agreements could be lawfully attacked only after all other means of control — such as directing it to land and submit to search — have been exhausted |
The parachuting-aircrew rule is the single most tested fact in Section 19B, and the discriminator is resistance: no resistance means no attack.
Enforcement and Rules of Engagement
"Each member of the armed services has a duty to comply with the law of war, which includes the refusal to comply with clearly illegal orders to commit law of war violations." Violations may be prosecuted by courts-martial under the UCMJ or through an international military tribunal.
Reporting violations: personnel who suspect or have information reasonably viewed as a violation "committed by or against U.S. personnel, enemy personnel, or any other individual, shall promptly report the violation to their immediate commander or the proper authority" — including violations by the enemy, allies, U.S. Armed Forces, or others. If the allegation involves or may involve a U.S. commander, the report should be made to the next higher United States command authority, and circumstances may require reporting to the nearest judge advocate, inspector general, an AFOSI special agent, or a security forces member.
Rules of engagement exist "to ensure use of force in an operation occurs according to national policy goals, mission requirements, and the rule of law," setting parameters for when, where, how, why, and against whom force may be used. All Airmen have a duty and a legal obligation to understand, remember, and apply rules of engagement. Standing rules of engagement are approved by the President and Secretary of Defense and issued by the Chairman of the Joint Chiefs of Staff.
Self-defense factors:
| Factor | What it means |
|---|---|
| De-escalation | When time and circumstances permit, forces committing hostile acts or demonstrating hostile intent should be warned and given the opportunity to withdraw or cease |
| Necessity | Focuses on the threat perceived by the individual — whether a hostile act has occurred or hostile intent is being demonstrated |
| Proportionality | Relates to the reasonableness of the response. Forces may use only the amount of force necessary to decisively counter the threat, reasonable in nature, duration and scope compared to the threat based on facts known at the time |
| Pursuit | Forces can pursue and engage a hostile force that has committed a hostile act or demonstrated hostile intent if those forces continue to do so; applicable rules may restrict pursuit across an international border |
Note that proportionality means two different things in this section — under the law of war principles it weighs incidental civilian harm against military advantage; under the rules of engagement it governs the reasonableness of a self-defense response. The exam sometimes tests whether you can tell the two usages apart.
Which law of war principle is violated by employing voluntary or involuntary human shields to protect military objectives?
Under the law of war, when may an Airman who has parachuted from a disabled aircraft be attacked?
How does the principle of honor distinguish a lawful ruse from prohibited perfidy?