The following describes the law of armed conflict (LOAC), also known as international humanitarian law, that applies to the ongoing Israel-Hamas war. We identify where the law is well settled and clear, and where it is less so.

We do not apply the law to any alleged facts. Indeed, whether any conduct violates the law would generally require a fact-driven, case-by-case analysis.

We hope this guidance will assist policymakers, diplomats, analysts, reporters, scholars, and the public at large.

1. Equal Application Principle

A bedrock principle is that the laws of war apply equally to all belligerent parties. Both sides must comply with LOAC.

That principle holds regardless of which side attacked first, whether the initial attack complied with international law, which side is acting in lawful self-defense, and irrespective of the relative justice of the causes involved.

 2. Sources 

LOAC treaties and customary international law govern the conflict between Israel and Hamas. Customary international law involves rules that States accept as binding international obligations that have not been codified in a treaty between the parties.

Every State in the world has ratified the Geneva Conventions of 1949. While some may dispute if or when exactly Palestine became a State for those purposes, the ICRC website includes Palestine’s accession to the 1949 Geneva Conventions (as well as other LOAC treaties). Common Article 3 to the Geneva Conventions sets out minimum standards for all parties to an armed conflict, including State forces and non-State armed groups. Those include key protections for civilians and for combatants who are no longer taking part in hostilities, such as detainees and the sick and wounded. Common Article 3 prohibits murder, cruel treatment, torture, outrages against personal dignity, and degrading or humiliating treatment for civilians and for combatants who have been captured or wounded.

Customary international law further regulates the conduct of hostilities by all belligerents, and provides protections for civilians and civilian objects (such as medical facilities, schools, etc. that are not in military use). The law requires belligerents to distinguish at all times between combatants and civilians (who can never be made the object of attack) and take all feasible precautions to minimize harm to civilians and civilian objects. Attacks that aim to target civilians, or that would cause excessive harm to the civilian population compared to the anticipated military gain (i.e., disproportionate attacks) are prohibited.

3. What body of LOAC applies to the conflict?: International versus non-international armed conflict

LOAC distinguishes between two types of conflict:

  • International armed conflict – a declared war or any other armed conflict between two or more States
  • Non-international armed conflict – an armed conflict between a State and a non-State organized armed group or an armed conflict between non-State armed groups

The distinction is important because the LOAC rules for a non-international armed conflict are less detailed (e.g., no prisoner of war status or combatant immunity for non-state armed groups) and there is a shorter list of war crimes applicable in a non-international armed conflict. For a comparison, scan the shorter list of war crimes for non-international conflicts versus international conflicts in the treaty of the International Criminal Court (Article 8).

For many of the issues involved in the Israel-Hamas conflict, the distinction is irrelevant. That’s because certain conduct (e.g., targeting civilians, taking of hostages) would be a violation of the law and a war crime regardless of the type of conflict. In other words, the conduct would come within the inner concentric circle — and amount to a war crime in both types of conflict. For some issues, however, the distinction between the type of conflict may be relevant (e.g., whether the use of human shields is a war crime or how difficult it would be to establish that it is; and whether disproportionate attacks on civilian infrastructure can be prosecuted by the International Criminal Court, to name two examples).

At a minimum, the laws of war applicable to non-international armed conflict apply to the Israel-Hamas conflict. However, there are several ways in which the situation might be considered an international armed conflict:

  • If Gaza is considered occupied territory, or becomes occupied in whole or in part during the course of the conflict;
  • If Palestine is considered a State;
  • If sufficient ties exist, or come to exist, between another State and Hamas such that the State wields overall control over Hamas, not only by equipping and financing it but also by coordinating or helping in the general planning of its military activity; or
  • If the conflict widens to include Israel directly fighting one or more States who join the fight alongside Hamas

4. What’s the difference between a violation of LOAC and a war crime? What is a “grave breach” of the Geneva Conventions?

LOAC imposes a broad set of obligations on parties to a conflict. It is a violation of international law to fail to comply with these obligations, but only some LOAC violations amount to a war crime. The term “war crime” denotes those LOAC violations that can result in individual criminal responsibility. Generally, only serious LOAC violations constitute a war crime. It depends on whether the obligation itself could ever incur criminal liability (some obligations don’t), and it depends on whether the actors have the requisite mental element, or state of mind, to satisfy the elements of a crime (“mens rea” in legalese).

The Geneva Conventions do not refer to “war crimes,” but rather “grave breaches.” All grave breaches constitute war crimes, even though not all war crimes are grave breaches. A grave breach can occur only in an international armed conflict. All States have universal jurisdiction over LOAC violations that qualify as a “grave breach,”, whether the States is involved in the conflict or not.

Generally, the mental state required to commit a war crime is “willfulness.” In the case of killing civilians (or destroying civilian infrastructure), willfulness includes both purposeful attacks on civilians as well as civilian casualties that result from certain forms of recklessness in targeting. Recklessness includes when an attacker consciously disregards a substantial and unjustifiable risk of harm to civilians or civilian objects.

Negligence is a lower threshold than recklessness. Negligence includes, for example, when an attacker should have known the probable consequence of their action was to kill civilians (or civilian objects) rather than combatants (or military objects).

Under the law of armed conflict, a State or non-State group may be legally on the hook if members of its armed forces kill civilians out of negligence, but the individual would not be criminally liable.

For more on that topic, read Ryan Goodman, Explainer: What Mental State is Required to Commit a War Crime?, Just Security, September 1, 2016.

5. Who qualifies as a “civilian” versus a “combatant” and why does it matter?

A fundamental objective of LOAC is to protect civilians – including individual civilians and the civilian population – and civilian objects from the harmful effects of hostilities. Parties to the conflict must distinguish between the civilian population and combatants and between civilian objects and military objectives and shall direct their operations only against military objectives. “Military objectives” are objectives that by their “nature, location, purpose, or use” make an “effective contribution” to military action, and whose total or partial destruction, capture, or neutralization, in the circumstances ruling at the time, offer a definite military advantage.

“Combatants” include (1) members of a State’s armed forces; (2) members of military or volunteer corps; (3) participants in a levée en masse; and (4) commanders and fighters in non-state armed groups. Combatants are subject to attack during hostilities unless they are captured or incapacitated, such as by injury.

“Civilians” include those individuals who do not belong to one of the combatant categories above. Civilians may not be made the object of attack. They lose their immunity from attack only if and for such time as they “directly participate in hostilities” (more on this below).

Note-1: De-activated reservists are generally considered civilians until they are mobilized.

The International Committee of the Red Cross, for example, states:

“For the purposes of the principle of distinction, membership in regular state armed forces ceases, and civilian protection is restored, when a member disengages from active duty and re-integrates into civilian life, whether due to a full discharge from duty or as a deactivated reservist.”

Note-2: Settlers, no matter how objectionable their conduct and in violation of international law, are civilians and may not be made the object of an attack.

Note-3: Civilians who are political supporters of an organized armed group or a State do not lose their status as civilians due to such support.

Note-4: Some non-State organizations – especially ones that exercise governance over a territory like Hamas – often have a military wing and a civilian wing. It is accordingly important to know when Israel states that it is targeting or has killed members of Hamas, what exactly that means in practice.

The separation between a military wing and civilian wing of a non-State actor can generally be fairly clear. More difficult cases may involve civilians who appear to exercise authority over military forces (consider the equivalent of a head of state who is also commander-in-chief) and law enforcement/police units depending on whether they take on a military role. Those cases on the margin should not distract from cases in the main wherein the distinction is often obvious.

Note-5: Members of the civil defense are civilians. Civil defense organizations are defined by the humanitarian tasks they perform in protecting the civilian population against dangers arising from hostilities (see ICRC Civil Defense Fact Sheet). Civil defense activities for the purpose of protecting civilians include warning, evacuation, management of shelters, and rescue.

6. Taking of hostages = war crime

Taking of civilian hostages is strictly forbidden at all times, by all parties, and would constitute a war crime in both international and non-international armed conflict.

7. Torture and rape = war crimes

Torture and rape are strictly forbidden at all times, by all parties, and would constitute war crimes in both international and non-international armed conflict.

8. Directly targeting civilians = war crime

Directly targeting civilians is strictly forbidden at all times, by all parties, and would constitute a war crime in both international and non-international armed conflict.

Note-1: All civilians are protected from being made the object of an attack. There are no subcategories of civilians. For instance, there is no category of “innocent civilians” as distinct from other civilians. Nor is any allowance given to attacking civilians who politically support an organized armed group or a State. They all count the same as any other civilian.

Note-2: The only time there is an exception to this rule, which is likely to have little or no relevance to the central issues in the ongoing Israel-Hamas conflict, is if and for such time as a civilian takes up arms (ie., joins the fight on either side). Only in that circumstance can a civilian lose their immunity from attack, and only for so long as they are directly participating in hostilities.

Note-3: The obligation to direct attacks only against combatants and military objects and never to direct attacks against civilians or civilian objects is known as the “basic rule” of international humanitarian law and comes under the “principle of distinction.” A related prohibition is that of indiscriminate attacks. Attackers must refrain from using weapons that cannot distinguish between military and civilian targets. For example, firing a missile that is of a nature to strike a military objective and civilians or civilian objects without distinction can amount to a war crime  (Additional Protocol I to the Geneva Conventions, Article 51(4)).

9. Attacks that disproportionately harm civilians = war crimes

A fundamental precept in LOAC is the rule of proportionality.

The rule is straightforward: Combatants must refrain from a military attack if the expected loss of civilian life or injury to civilians incidental to the attack would be excessive in relation to the concrete and direct military advantage expected to be gained.

Violations of this rule can be a war crime.

It is important to recall the state of mind required for conduct to be criminal. Purposefully or recklessly killing civilians in violation of the rule of proportionality can amount to a war crime. In contrast, an attack that results in disproportionate loss of civilian life due to negligence would be unlawful, though not criminal.

Proportionate to what? In public discourse, commentators often compare the number of civilians lost on one side of a conflict versus the other. That is not what is meant by proportionality under the laws of war applicable during armed conflict. Those comparisons may be best discussed in terms of morality or in terms of a separate body of international law governing the necessary and proportionate use of force in self-defense. In LOAC, a proportionality assessment takes into account the expected civilian harm as compared to the concrete and direct military advantage that is expected to be gained as of the time of the attack.

10. Targeting civilian infrastructure and disproportionality targeting civilian infrastructure = war crime

The same two rules just discussed with respect to civilian persons (8 and 9) also apply to civilian objects. The protection of civilian infrastructure is often a vitally important issue in urban warfare.

Directly targeting civilian objects is strictly forbidden and constitutes a war crime in both international and non-international armed conflict. Likewise, combatants must refrain from a military attack if the expected damage to civilian objects incidental to the attack would be excessive in relation to  the concrete and direct military advantage expected to be gained. Violations of that rule of proportionality may amount to a war crime if done purposefully or recklessly.

Important note on residential apartment buildings with military units inside.  

Israel apparently adopts a highly unusual view of LOAC that would allow greater license to destroy an entire residential apartment building in which an enemy military facility is found — and to do so without the standard proportionality analysis. The generally accepted view is that an attack on a civilian apartment building in such cases must consider whether the civilian infrastructure that is expected to be destroyed is excessive in relation to the expected military advantage (ICRC, United States, International Law Association; ICRC report surveying States’ views and leading scholarship). The outlier position adopted by Israel is that “as a matter of law, the building is a single military objective, and therefore damage to other parts of the building need not be considered as collateral damage” (Merriam & Schmitt 2015; Eli Bar-On 2021). This conception of the rule does not appear to include a limiting principle that would apply to  other civilian objects, including medical facilities, houses of worship, schools, and the like.

Note-1: The military manual of at least one other State – Denmark – appears to agree with Israel’s legal position. However, that manual also states: “Danish armed forces are required to recognise damage to the non-military ‘share’ of the dual-use object as collateral damage when the non-military share is of particular and direct importance to protected persons” (emphasis in original).

Note-2: To avoid confusion, it is important to make clear that Israel’s legal position would still consider any loss of civilian life or injury to civilians in the proportionality analysis. It is the civilian infrastructure – the building itself – which drops out of their equation.

11. All feasible precautions to minimize civilian harm

Combatants must take all feasible precautions to minimize incidental loss of civilian life, injury to civilians and damage to civilian objects (Additional Protocol I to the Geneva Conventions, Article 57). “In the conduct of military operations, constant care shall be taken to spare the civilian population,” as set forth in Protocol I to the Geneva Conventions.

A violation of the rule of feasible precautions is clearly a violation of LOAC. That said, surprising to many, as a matter of international law, such a violation generally cannot incur criminal liability. Of course, systematic violation of this rule may provide strong evidence of criminal intent to purposefully or recklessly kill civilians or a disproportionate number of civilians (or damage to civilian objects).

12. Human shields

Defenders’ obligations: The use of civilians as involuntary human shields is unlawful. Such conduct is a war crime in international armed conflict and likely, but not definitely, in non-international armed conflict. For example, the sections of the International Criminal Court treaty covering war crimes in international armed conflict include the offense of “utilizing the presence of a civilian or other protected person to render certain points, areas or military forces immune from military operations.” No such offense is contained in the sections on war crimes in non-international armed conflict.

Attackers’ obligations: Defenders are certainly responsible for the deaths of civilians that they use as human shields. Nevertheless, individuals who are involuntary human shields do not lose their right to be treated as civilians. As the Israeli High Court explained in 2009, “What is the law regarding civilians serving as a ‘human shield’ for terrorists taking a direct part in the hostilities? Certainly, if they are doing so because they were forced to do so by terrorists, those innocent civilians are not to be seen as taking a direct part in the hostilities. They themselves are victims of terrorism.”

The enemy’s use of civilians as involuntary human shields does not relieve attacking forces from their own responsibilities. In conducting an attack, commanders must take into account those civilians used as involuntary human shields both in the proportionality analysis and in the obligation to minimize harm to civilians.

For more information, readers may be interested in Beth Van Schaack, Human Shields in International Humanitarian Law: A Guide to the Legal Framework, December 7, 2016.

13. Collective punishment

Collective punishment is strictly forbidden and can amount to a war crime in both international and non-international armed conflicts. Collective punishment includes the imposition of penalties on civilians for actions that they themselves did not personally commit.

As early as the 1949 Geneva Convention on Protection of Civilians, States made clear that this prohibition “rul[es] out the idea that the community might bear at least a passive responsibility” (ICRC Commentaries).

14. Siege warfare

The laws of war permit siege warfare – otherwise known as “encirclement” – against enemy armed forces and other military objectives, but the laying of sieges must comply with all relevant LOAC rules.

The principle of distinction – a siege must be directed only against enemy armed forces and military objectives while exercising constant care to spare civilians and civilian objects.

Among the most important conditions on siege warfare is the prohibition on starvation of civilians. For additional reading on this topic, see Tom Dannenbaum, The Siege of Gaza and the Starvation War Crime, Just Security, October 11, 2023; Beth Van Schaack, Siege Warfare and the Starvation of Civilians as a Weapon of War and War Crime, Just Security, February 4, 2016.

The prohibition on starvation may be met through deprivation of relief supplies. The International Criminal Court treaty states, in the context of international armed conflict, “Intentionally using starvation of civilians as a method of warfare by depriving them of objects indispensable to their survival, including wilfully impeding relief supplies as provided for under the Geneva Conventions.”

The principle of proportionality – some experts conclude that, like the law of blockades, a siege must comply with the principle of proportionality. On this view, the impact on the civilian population must not be excessive in relation to the concrete and direct military advantage expected to be gained from the siege (Maxime Nijs, International Review of the Red Cross: 2020, including sources in fn. 83; Michael Schmitt, Sqn. Ldr. Kieran Tinkler and Durward Johnson, The UN Yemen Report and Siege Warfare, Just Security, September 12, 2019). See also U.S. Department of Defense, Law of War Manual § 5.20.2 (2023) (“Military action intended to starve enemy forces, however, must not be taken where it is expected to result in incidental harm to the civilian population that is excessive in relation to the military advantage anticipated to be gained.”).

See also the section below on access to humanitarian relief.

15. Access to humanitarian relief

“The parties to the conflict must allow and facilitate rapid and unimpeded passage of humanitarian relief for civilians in need, which is impartial in character and conducted without any adverse distinction,” states the ICRC’s assessment of governing international law (see also Additional Protocol II to the Geneva Conventions, Article 18(2); Additional Protocol I to the Geneva Conventions, Articles 69-70). Consent of the State is required, but such consent cannot be withheld arbitrarily. For competing views on what is meant by arbitrarily withholding consent for relief supplies, see Akande and Gillard: 2016 and Watts: 2019.

Note-1: There is one exception to the rule on consent: the consent of an occupying power cannot be withheld (Geneva Convention on the Protection of Civilians, Article 59).

Note-2: The ICRC Commentaries to Additional Protocol II state:

“The fact that consent is required does not mean that the decision is left to the discretion of the parties. If the survival of the population is threatened and a humanitarian organization fulfilling the required conditions of impartiality and non-discrimination is able to remedy this situation, relief actions must take place. In fact, they are the only way of combating starvation when local resources have been exhausted. The authorities responsible for safeguarding the population in the whole of the territory of the State cannot refuse such relief without good grounds. Such a refusal would be equivalent to a violation of the rule prohibiting the use of starvation as a method of combat as the population would be left deliberately to die of hunger without any measures being taken.”

16. Forcible displacement of civilians versus lawful evacuation

Forcible displacement of a civilian population is unlawful both in international and non-international armed conflict. It is considered a war crime in an international armed conflict and might be a war crime as well in a non-international armed conflict. However, if conducted as part of an attack on a civilian population, the forcible transfer of civilians can amount to a crime against humanity (ICRC; International Criminal Court treaty), whether in an international or non-international armed conflict or no armed conflict at all.

The prohibition on forcible displacement is subject to an important exception “in cases where the security of the civilians involved or imperative military reasons (such as clearing a combat zone) require the evacuation” (ICRC Rule 129 (emphasis added)).

An occupying power, for example, has the legal right, and in certain circumstances a duty, to perform an evacuation for the safety of civilians. The ICRC Commentaries to the Geneva Convention on Protection of Civilians states: “If therefore an area is in danger as a result of military operations or is liable to be subjected to intense bombing, the Occupying Power has the right and, subject to the provisions of Article 5, the duty of evacuating it partially or wholly, by placing the inhabitants in places of refuge.”

The difference between unlawful forcible displacement and lawful evacuation may turn on the following conditions:

  1. Whether (a) the purpose is to protect civilians from the effects of military attacks, or (b) it is for an illicit purpose such as to change the demographic makeup of an area or indefinitely remove inhabitants as a security buffer;

The ICRC Commentary states: “Clearly, imperative military reasons cannot be justified by political motives. For example, it would be prohibited to move a population in order to exercise more effective control over a dissident ethnic group.”

Official statements blaming the local civilian population for atrocities committed by enemy forces would be relevant evidence of an illicit purpose. It would have to be determined whether the sentiment expressed in such statements has shaped the policy of removal.

  1. Whether the measure would remove civilians to a third country;

In non-international armed conflicts “evacuations may never involve displacement outside the national territory” (ICRC Rule 129; Additional Protocol II to the Geneva Convention, Article 17(2)).

  1. Whether the measure is effectuated by shutting off food, water, and other essentials to the civilian population.

Relevant here is Additional Protocol II to the Geneva Convention, which states: “Should such displacements have to be carried out, all possible measures shall be taken in order that the civilian population may be received under satisfactory conditions of shelter, hygiene, health, safety and nutrition” (Article 17(1)).

Note: Forcible displacement can occur “by means of threats” (ICRC Commentary).

17. Criminal enforcement

International Criminal Court

In 2015, Palestine deposited an instrument of accession with the International Criminal Court.  The past and current ICC Prosecutors and a three-judge panel (a “pre-trial chamber”) concluded on this basis that the Court has jurisdiction over crimes allegedly committed in Gaza. That claim of jurisdiction is not without legal controversy, as Israel has long contested it.

In the days following the Hamas massacre inside Israel, the ICC Prosecutor Karim A. A. Khan KC stated, in an interview, that the Court’s jurisdiction reaches Hamas’s conduct inside Israel. He explained that the Court’s jurisdiction includes crimes committed by nationals of State Parties (see International Criminal Court treaty Article 12(2)(b)).

National courts’ war crimes trials

Courts in foreign countries might be able to hold trials for war crimes committed outside their own territory even if the alleged perpetrator(s) and the victim(s) are not nationals of the State where the trial takes place. Exercising the authority of “universal jurisdiction,” Germany has led the way including holding trials for war crimes committed in Syria.

The United States recently passed legislation allowing the Justice Department to prosecute war crimes in such cases if the perpetrator is later located in the United States.

States in which such trials might take place would be on even firmer legal footing if the victim(s) or perpetrator(s) are nationals of their State.

IMAGE: (L) Members of the Ezz-Al Din Al-Qassam Brigades, the armed wing of the Hamas movement, parade on a truck with rockets in a street in Khan Yunis, in the southern Gaza Strip on May 27, 2021 (Thomas Coex/AFP via Getty Images); (R) An Israeli soldier stands atop a tank in a field near the kibbutz Beeri in southern Israel on October 14, 2023, close to the spot where 270 revellers were gunned down or burnt in their cars by Hamas gunmen at the Supernova music festival in the Negev desert seven days earlier (Thomas Coex/AFP via Getty Images).