Law of Armed Conflict — Military Rules of Engagement and War Crimes

The Law of Armed Conflict (LOAC) — also called International Humanitarian Law (IHL) — is the body of international law that governs the conduct of armed conflict: who may be targeted, what weapons may be used, how prisoners must be treated, and what obligations apply to occupying powers. For U.S. military forces, LOAC is not merely aspirational; it is binding law implemented through treaties that the United States has ratified, customary international law, federal statutes (primarily 10 U.S.C. § 818 and 18 U.S.C. § 2441), and the DoD Law of War Manual (2015, revised 2023). Every U.S. service member receives LOAC training; every commander has a Judge Advocate General (JAG) officer available for legal review of targeting decisions. Violations can result in courts-martial, federal criminal prosecution, and — in some circumstances — prosecution by international tribunals.

Current Law (2026)

Legal Authority

• 10 U.S.C. § 818 — Grants military courts (courts-martial) jurisdiction over law of war violations committed by members of the armed forces and, in certain circumstances, persons accompanying them; the primary domestic hook for prosecuting LOAC violations within the military justice system
• 18 U.S.C. § 2441 (War Crimes Act) — Federal criminal statute making it a crime for U.S. nationals (military or civilian) or for persons acting against U.S. nationals to commit grave breaches of the Geneva Conventions; enumerated grave breaches include willful killing, torture, inhumane treatment, and willfully depriving a protected person of a fair trial; punishable by up to life imprisonment, or death if the victim dies
• 18 U.S.C. § 2340A (Torture Statute) — Implements the Convention Against Torture; prohibits torture outside the United States by U.S. nationals or by any person in the United States; mental suffering is included in the definition; up to 20 years imprisonment (life if victim dies)
• 10 U.S.C. § 130e — Reporting requirements for "sensitive military operations" — DoD must provide congressional armed services committees with notification and description of any lethal action or capture operation in areas outside of active hostilities
• Executive Order 13732 / Biden Civilian Casualty Policy: Obama's EO 13732 required annual public reporting on civilian casualties from U.S. strikes; Biden's 2021 policy expanded these requirements and required a Civilian Harm Mitigation and Response Action Plan (CHMRAP); Trump administration began rescinding Biden-era civilian harm requirements in 2025, reinstating Trump first-term NSPM-11 approach

How It Works

The Five Core LOAC Principles

Military Necessity: Military forces may use only the force required to achieve a legitimate military objective. Destruction of civilian property, capture of civilians, and denial of resources are permissible only when militarily necessary.

Distinction: Combatants and civilian objects must be distinguished from civilians and civilian objects at all times. Attacks may only be directed at combatants (lawful targets) and military objectives. Civilians who "directly participate in hostilities" lose protection for the duration of their participation — a contested standard in counterterrorism operations where fighters blend with civilian populations.

Proportionality: Incidental civilian casualties and damage to civilian property must not be excessive in relation to the concrete and direct military advantage anticipated. The proportionality calculation — collateral damage estimation (CDE) — is a commander's judgment informed by JAG advice. There is no formula; it requires weighing expected civilian harm against anticipated military advantage in good faith.

Humanity: Combatants are prohibited from using weapons and methods designed to cause superfluous injury or unnecessary suffering. This principle underlies bans on chemical and biological weapons, blinding laser weapons (Protocol IV to the CCW), and expanding bullets in warfare.

Precaution: Commanders must take feasible precautionary measures to minimize civilian harm, including choosing the method and timing of attacks, providing warnings where feasible, and suspending attacks when it becomes apparent that targets are civilian.

Rules of Engagement (ROE)

Rules of Engagement are the classified operational orders derived from LOAC principles and policy that tell commanders and individual service members what they may and may not do in specific operational situations. The framework operates at three levels:

Standing Rules of Engagement (SROE): Issued by the Chairman of the Joint Chiefs of Staff (CJCSI 3121.01B); apply globally to all U.S. forces at all times; establish the baseline self-defense right. Under SROE, U.S. forces always have the inherent right of self-defense — including anticipatory self-defense against a hostile act or demonstrated hostile intent. SROE are unclassified in framework but classified in specific procedures.

Theater-Specific ROE: Geographic combatant commanders modify SROE for their area of operations; may be more permissive (additional authorities granted for specific missions) or more restrictive (no-strike zones, weapons restrictions, escalation of force procedures). Afghanistan CJOA ROE, for example, went through multiple iterations as the conflict evolved from major combat to counterinsurgency to advise-and-assist.

Mission-Specific ROE: Issued by task force commanders for specific operations; most granular level; may authorize specific weapons effects, geographies, or target categories.

Key ROE Concepts:

• PID (Positive Identification): Before engaging a target, the shooter must have positive identification that the target is a lawful military objective
• CDE (Collateral Damage Estimation): Structured process for estimating civilian casualties before approving a strike; JDPI (Joint Desired Point of Impact) and CEP (circular error probable) calculations inform CDE
• Escalation of Force (EOF): Required procedures for warning civilian vehicles or personnel before using lethal force at checkpoints or in convoy protection; hand signals, flares, warning shots
• LOAC Card: Wallet-sized laminated card carried by each service member summarizing key ROE; updated for each deployment

Targeting Law

Lawful Targets: Members of organized armed forces; civilians who directly participate in hostilities; specific military objectives (nodes, systems, facilities that provide effective contribution to military action and whose destruction offers definite military advantage)

Protected Persons and Objects: Civilians; civilian objects; medical personnel, facilities, and transport (marked with Red Cross/Crescent); POWs; cultural property (Hague Convention 1954); objects indispensable to civilian survival (food, water, agricultural infrastructure)

High-Value Individual (HVI) Targeting: The "kill or capture" targeting of specific named individuals — JPEL (Joint Prioritized Effects List) in Afghanistan; similar lists in other theaters — requires legal review by a JAG and approval at an appropriate level of command (the "sensitive strike" process). For strikes outside declared theaters of hostilities, presidential-level approval was required under Obama policy; NSPM-11 (Trump 2017) delegated more authority to SecDef and COCOM commanders; Biden policy required White House-level approval for strikes in Somalia and other non-declared war zones; Trump 2025 has reinstituted more permissive delegation.

Pattern of Life Analysis: Using ISR to develop understanding of a target's movements and associations over time to support PID; controversial because it can lead to confirmation bias in targeting decisions (the "disposition matrix" framework developed during Obama administration).

War Crimes: Investigation and Prosecution

The UCMJ Framework (most common path):

• Article 93 — cruelty and maltreatment of persons subject to military orders
• Article 118 — murder
• Article 128 — assault
• Article 134 — general article (conduct prejudicial to good order and discipline, or conduct unbecoming)

Investigation is conducted by Army CID, NCIS (Navy/Marines), or OSI (Air Force). Investigation findings go to a commander who decides whether to refer charges to a general court-martial. The Manual for Courts-Martial (MCM) governs proceedings; JAG prosecutors and defense counsel are both Judge Advocates. Military judges preside.

The War Crimes Act (18 U.S.C. § 2441) is used less frequently; it applies to civilians accompanying the military and to extraterritorial jurisdiction cases, prosecuted by DOJ. In practice, DOJ has rarely used § 2441; most cases are handled through the UCMJ.

High-Profile Cases:

• Abu Ghraib (2003–2004): Documented torture and abuse of Iraqi detainees at Abu Ghraib prison; 11 enlisted soldiers convicted; highest-ranking officer convicted was Brig. Gen. Janis Karpinski (demoted to Colonel); no senior civilians or generals from OSD charged; ongoing controversy about command responsibility
• Haditha Killings (2005): Marines killed 24 Iraqi civilians following IED attack; charges originally filed against 8 Marines; all charges eventually dropped or dismissed except Lt. Frank Wuterich (guilty plea to negligent homicide, no prison time; sentence: rank reduction)
• Robert Bales Massacre (2012): Staff Sergeant massacred 16 Afghan civilians in Kandahar; pleaded guilty to avoid death penalty; sentenced to life without parole (Fort Leavenworth)
• Eddie Gallagher (2019): Navy SEAL Team Seven chief prosecuted for killing an ISIS prisoner and posing with the corpse; acquitted of murder by court-martial; convicted only of posing for the photo (demoted); Trump pardoned Gallagher (restored to E-7), overriding Navy's revocation of his Trident pin; SECDEF Spencer resigned in protest
• Clint Lorance (2019): Army lieutenant convicted of murder for ordering subordinates to shoot unarmed Afghan civilians; sentenced to 19 years; pardoned by Trump

Command Responsibility: Under the Yamashita doctrine (established by U.S. military tribunal after WWII), commanders can be held responsible for war crimes committed by subordinates if the commander knew or should have known of the crimes and failed to prevent or punish them. U.S. courts-martial have applied this principle inconsistently; Abu Ghraib resulted in no command responsibility convictions above lieutenant colonel level.

Detention Law

Enemy Combatant Detention: Under LOAC, armed forces may detain enemy combatants without criminal charge for the duration of hostilities. This is law-of-war detention, not criminal detention, and does not require Miranda warnings, access to civilian counsel, or trial.

Geneva Convention Categories:

• POW status (Convention III): Lawful combatants captured in international armed conflict; entitled to specific protections including name/rank/number only requirement, adequate food and medical care, protection from public curiosity, repatriation after hostilities
• Civilian internees (Convention IV): Protected persons detained in occupied territory
• Common Article 3 (applies to non-international armed conflicts): Minimum baseline protections — no murder, torture, cruel treatment, or humiliating and degrading treatment; trial by a regularly constituted court with judicial guarantees

Post-9/11 Detention Framework: The Bush administration's "unlawful enemy combatant" framework attempted to deny both POW status (Convention III) and civilian protections (Convention IV) to Al-Qaeda and Taliban detainees. Supreme Court cases (Hamdi v. Rumsfeld, 2004; Hamdan v. Rumsfeld, 2006; Boumediene v. Bush, 2008) progressively constrained executive detention authority, holding that Common Article 3 applies to all detainees and that Guantanamo detainees retain habeas corpus rights.

Guantanamo (as of April 2026): 30 detainees remain; median detention period exceeds 20 years; ongoing habeas proceedings in D.C. Circuit; Biden failed to close the facility; Trump pledged to expand it

Military Commissions: Created by the Military Commissions Act (2006, amended 2009) for trial of "unprivileged enemy belligerents" for offenses under the law of war; 9/11 trials (KSM and four co-defendants) remain in pre-trial proceedings 23 years after the attacks due to recurring procedural challenges

Autonomous Weapons and AI

DoD Directive 3000.09 (2012, updated 2023) requires that lethal autonomous weapons systems (LAWS) have "appropriate levels of human judgment over the use of force." The policy does not define "meaningful human control" with precision, creating ongoing legal and policy debate. Current U.S. position: fully autonomous lethal systems require dedicated review before fielding; semi-autonomous systems (human in the loop for each kill decision) are permissible.

The International Committee of the Red Cross (ICRC) and a majority of states in the Convention on Conventional Weapons (CCW) process support negotiating an international treaty on LAWS. The United States has opposed a treaty, preferring politically binding guidelines. This debate will intensify as drone swarm technologies mature.

How It Affects You

If you are an active-duty service member or officer: Every deployment brief includes ROE training; the ROE card in your pocket is the operationally relevant summary, but the underlying legal framework matters when situations arise that the card didn't anticipate. Your right of self-defense is always inherent under SROE — you never need permission to defend yourself or your unit against a hostile act. When in doubt about a targeting decision (especially outside direct combat), call your unit JAG before engaging: JAGs are required to be available 24/7 in deployed environments and their opinion provides legal protection even if later questioned. A good-faith legal judgment call, documented at the time, is your strongest protection against post-hoc prosecution. If you witness potential war crimes, reporting through your chain of command or directly to CID/NCIS is legally required; failing to report can itself create criminal exposure under Article 92 (dereliction of duty).

If you are a JAG officer, military defense attorney, or civilian defense counsel: The most contested LOAC legal questions in current practice involve: (1) the "direct participation in hostilities" standard for civilians who briefly take up arms and then return to civilian status (the "revolving door" problem); (2) whether pattern-of-life-based targeting without individual PID satisfies LOAC distinction requirements; (3) the scope of command responsibility in cases where senior leaders approved targeting frameworks under which subordinates committed violations. For defense of service members accused of war crimes, the specific ROE in effect at the time of the alleged incident are discoverable and often determinative — obtain the classified ROE through appropriate defense counsel channels (CMAAF — Classified Material Appellate Facility). Presidential pardons of Gallagher and Lorance complicate clemency strategy by signaling that political factors, not legal merit, drive executive clemency in high-profile cases.

If you are a policy analyst, NGO researcher, or human rights advocate: The most productive public accountability tools are: (1) Annual DoD Civilian Casualty Reports (released pursuant to EO 13732, now subject to Trump rollback — check at defense.gov for current reporting obligations); (2) Airwars (airwars.org) — the most comprehensive non-government database of civilian casualty allegations from U.S. and coalition strikes; (3) U.S. Central Command's press releases (CENTCOM.mil/MEDIA) which announce strikes and sometimes acknowledge civilian casualties; (4) Inspector General reports on law of war compliance, available at oig.defense.gov. ICC jurisdiction over U.S. nationals is effectively blocked because the United States is not a party to the Rome Statute; the International Court of Justice can hear state-to-state cases. U.S. legal advocacy on LOAC compliance is most effectively pursued through congressional oversight (10 U.S.C. § 130e reports), DoD IG channels, and litigation under the Administrative Procedure Act challenging targeting frameworks rather than seeking individual criminal accountability.

If you are a civilian contractor or private military company employee operating in a conflict zone: The War Crimes Act (18 U.S.C. § 2441) applies to U.S. nationals regardless of employment status — a contractor committing a grave breach of the Geneva Conventions faces federal prosecution. The Military Extraterritorial Jurisdiction Act (MEJA, 18 U.S.C. § 3261) also applies to DoD contractors for any felony committed outside the United States. The UCMJ was amended in 2006 to cover civilians accompanying the armed forces in declared war — the scope of that coverage remains legally contested. Practical protections: ensure your contract specifies ROE compliance requirements and that your employer provides LOAC training; maintain contemporaneous documentation of any orders you received and your actions; if you witness a potential violation, preserve evidence and consult an attorney before making any statements to CID or NCIS (you have no equivalent to military Article 31 rights, but Fifth Amendment protections apply).

If you follow the Russia-Ukraine conflict or U.S. weapons transfers to allies: LOAC compliance debates directly affect U.S. foreign policy. U.S. law (including Leahy Law, 22 U.S.C. § 2378d, and 10 U.S.C. § 362) prohibits security assistance to foreign military units credibly alleged to have committed gross violations of human rights. If you are a Congressional staffer or NGO researcher tracking weapons transfers, State Department's Leahy vetting determinations are partially available through FOIA. The ICC's arrest warrant for Vladimir Putin (for deportation of Ukrainian children) marked the first arrest warrant for a sitting head of a nuclear power; the United States, not being a Rome Statute party, is not legally obligated to enforce it but has expressed support. U.S. assistance to Israel has generated active LOAC compliance debates under both the Biden and Trump administrations, implicating Section 620I of the Foreign Assistance Act (restricting aid when a country obstructs humanitarian access) and DoD Directive 2311.01 on LOAC compliance.

State Variations

LOAC is entirely a federal and international domain; states have no authority to modify, enforce, or create exceptions to the law of armed conflict. Several state-level intersections exist:

• National Guard in State Active Duty: When National Guard soldiers are on state active duty (not federalized), they are governed by state law, not federal military law. However, they remain bound by LOAC as a matter of customary international law if deployed in an armed conflict context.
• State War Crimes Accountability Legislation: Some states have enacted legislation (e.g., California SB 1382 in 2022, ultimately vetoed) that would have prohibited state pension funds from investing in companies whose employees were accused of war crimes. These efforts are largely symbolic, as federal law governs the underlying conduct.
• State Court Jurisdiction: State courts have no jurisdiction over war crimes or UCMJ violations; those claims must be brought in federal court or through courts-martial.

Implementing Regulations

• DoD Law of War Manual (2015, updated June 2023, ~1,200 pages): The authoritative DoD implementation document; published by DoD General Counsel's office; covers targeting, detention, occupation, cyber operations, and autonomous weapons; available at defense.gov/lawofwarmanual
• DoD Directive 2311.01 — DoD Law of War Program; requires all DoD components to implement LOAC, conduct training, investigate alleged violations, and report through chains of command
• DoD Instruction 3000.11 — Civilian Harm Mitigation and Response (CHMR, 2023); implementing guidance for the Biden-era CHMRAP; requires commanders to estimate, mitigate, and respond to civilian harm; status under Trump review 2025
• DoD Directive 3000.09 — Autonomous Weapons; requires appropriate human judgment before lethal autonomous systems are deployed; updated 2023
• CJCSI 3121.01B — Standing Rules of Engagement; classified operational guidance implementing LOAC for all U.S. forces

Pending Legislation

• Civilian Harm Reduction Act (proposed, 2025): Would codify portions of Biden's CHMRAP into statute, making civilian harm mitigation reporting requirements law rather than executive policy subject to rescission; introduced by bipartisan Senate coalition after Trump rollbacks
• War Crimes Accountability Act: Reintroduced proposal to expand 18 U.S.C. § 2441 to cover "serious violations" of the laws of war beyond the current "grave breaches" limitation; would close the gap between customary international law and U.S. statutory coverage
• LAWS Treaty Opposition Resolution: Congressional resolutions in 2025 expressing opposition to any international treaty limiting autonomous weapons that would constrain U.S. military AI development — politically significant but not legally binding
• ICC Relationship Legislation: Competing proposals — one to restore the American Servicemembers' Protection Act (ASPA) penalties for cooperating with ICC; another to explore U.S. re-engagement with the Rome Statute under conditions

Recent Developments

• Russia-Ukraine LOAC Violations (2022–2026): Russia's targeting of civilian electrical infrastructure, apartment buildings, hospitals, and maternity wards has generated thousands of documented potential LOAC violations. The Ukrainian Prosecutor General and International Criminal Court have opened investigations; ICC issued arrest warrants for Putin and Russian Children's Commissioner Lvova-Belova. U.S. provides intelligence to ICC prosecutors (not formally a party but cooperating under Biden administration; Trump's relationship with ICC is uncertain).
• U.S. Aid to Israel and LOAC Debate (2023–2025): Gaza conflict generated significant U.S. domestic legal debate over whether Israel's operations — specifically civilian casualty rates, restrictions on humanitarian aid, and destruction of civilian infrastructure — constitute violations that trigger U.S. statutory restrictions on weapons transfers. Biden administration's National Security Memorandum-20 (NSM-20) assessment process and its handling of the Leahy Law and Section 620I obligations were heavily criticized by human rights organizations; Trump administration removed most restrictions on weapons transfers.
• Trump Pardons Impact (2019, ongoing): The Gallagher and Lorance pardons created a doctrinal gap in command accountability — if political intervention reliably follows conviction, the deterrent effect of the UCMJ war crimes framework is weakened. SEAL and SOF leadership have expressed private concern about the signal sent to junior operators.
• Civilian Harm Mitigation Rollback (2025): Trump administration rescinded several Biden-era policies requiring enhanced civilian harm reporting and post-strike reviews. Advocacy organizations filed administrative challenges; GAO began a review of whether the rollback complied with statutory requirements under 10 U.S.C. § 130e reporting obligations.
• DoD Law of War Manual Update (June 2023): The Biden-era update added significant new material on cyber operations (determining which cyberattacks constitute "attacks" under LOAC and what objects are "military objectives" in cyberspace) and on the law applicable to autonomous weapons; the cyber targeting section remains the most actively contested portion in legal scholarship.