What International Law Has to Say About the Israel-Hamas War

The atrocities Hamas committed against Israel on October 7 have sent shockwaves around the world and prompted the Israeli government to embark on a war of still-unknown magnitude and character against the Palestinian militant group.

Israel’s military campaign in the Gaza Strip seeks to fulfill several objectives, including the destruction of Hamas and the rescue of hostages, that are strictly regulated by international law. Observing these legal guardrails, as Israel has declared it will do, will make the conflict complicated and risky, particularly because Israel’s actions will be scrutinized by various observers, including other governments, the United Nations, the International Criminal Court, legal scholars, civil society, and the general public. The large number of civilian casualties in a fiery explosion at a Gaza hospital has underscored how an unconstrained war could take a grim human toll.        

Hamas’s War Crimes

Hamas’s killing of at least 1400 Israeli civilians (including children) during its surprise attack on Israeli territory violated provisions of international humanitarian law that are designed to protect civilians and their property during war. They include Common Article 3 of the 1949 Geneva Conventions, which requires humane treatment of civilians and noncombatants; Article 51 of the conventions’ Protocol I, which protects civilian populations from attack; and a host of provisions on war crimes and crimes against humanity in Articles 7 and 8 of the Rome Statute [PDF] of the International Criminal Court (ICC), which reflect customary international law and apply to Hamas leaders and fighters. Moreover, Hamas’s continuous, indiscriminate rocket attacks against Israeli targets put civilian structures and individuals at risk, also violating these treaty provisions and customary international law.

Is Hamas covered by international law?

There continues to be a rather strained debate among governments and legal scholars about applying various fields of international law to nonstate actors such as Hamas, including questions about the legal obligations of states that these actors come into conflict with. For example, in the United States, the George W. Bush administration advanced a “legal black hole” argument during the so-called war on terrorism that followed 9/11, claiming that al-Qaeda and the Taliban were nonstate actors and therefore unprotected by the 1949 Geneva Conventions. However, the U.S. Supreme Court discredited that legal argument in 2006, ruling that Common Article 3 of the conventions did apply to the U.S. war with al-Qaeda.

Israel and the “state of Palestine,” which is recognized by most countries as comprising the West Bank, Gaza, and East Jerusalem, are ratified parties of the four Geneva Conventions of 1949. Israel has not ratified the first and second protocols of the conventions, which in 1977 further regulated protection of civilians, property, and the environment during war. One of the prominent provisions is Article 75 of Protocol I, which Washington has long viewed as part of customary international law and thus the provision would bind not only the United States but also Israel. It requires that persons held by a combatant power shall be treated humanely in all circumstances and provides a detailed list of prohibited conduct. A plurality of Supreme Court justices in the 2006 decision stressed Article 75’s customary application. Palestine has ratified all three protocols, so as a state party, it is undeniably bound to their terms. Hamas, particularly as a de facto governing authority in Palestine (namely, over Gaza) with control over its own militant forces, is obligated as part of the state of Palestine to comply with the Geneva Conventions and its three protocols.

The state of Palestine also is a state party of the Rome Statute of the International Criminal Court (ICC), which means that Hamas leaders and personnel can be held accountable for committing genocide, crimes against humanity, or war crimes on, for example, Israeli territory or in Gaza. Israel, like the United States and dozens of other countries, is not a state party of the Rome Statute, but the ICC prosecutor will scrutinize its military actions in Gaza, the territory of a state party.

Israel’s Self-Defense

Israel’s primary objectives are self-defense in response to the Hamas attacks and ensuring the future security of Israel. Article 51 of the UN Charter permits actions of “inherent” self-defense derived from customary international law, and it does not limit that right to actions against the conventional armed forces of another state. The UN Security Council can choose not to take any action to reinforce or circumscribe this right of self-defense—and, regardless, the body has long been essentially paralyzed by the fracture between Western permanent members and the twosome of Russia and China, as amply demonstrated during the council’s inconclusive meeting on October 16.

Deeply associated with Israel’s self-defense measures is the government’s stated intention to terminate Hamas entirely. International law does not explicitly prohibit the use of force to eliminate an organization such as Hamas, which Israel, the United States, and many other countries consider a terrorist group. It remains important, however, that Israel’s use of force to achieve this aim abides by the right of self-defense under the UN Charter and is in accordance with the law of armed conflict and international humanitarian law.

What should Israel do to comply with international humanitarian law? 

Israel has fundamental legal obligations to abide by during its campaign against Hamas. Heavily charged statements by some Israeli officials need to be separated from sound legal policy. In brief, Israel must meet several standards:

• It must not use starvation (including deprivation of food, water, and other essentials for survival) of Gaza’s civilian population as a weapon of war against Hamas or for any reason.
• It must take every possible step to target only Hamas militants and their military infrastructure, and to minimize civilian casualties and the destruction of civilian infrastructure. The Israeli air and artillery campaign, as well as its ground warfare, must be guided by the immutable legal principles of humanity, distinction, proportionality, and military necessity.
• It must allow for the return of displaced civilians after the conflict. While a temporary evacuation of civilians from a theater of combat can be legally requested, it would be unlawful to permanently displace the civilian population from their homes. The circumstances in Gaza today create enormous hardship for hundreds of thousands of Palestinian civilians, and Israel should take measures to ameliorate these difficult conditions. The visits of U.S. President Joe Biden and U.S. Secretary of State Antony Blinken to the Middle East this week focused in part on what Israel and other nations and organizations can do to address the humanitarian plight of Palestinians in Gaza.

Rescuing Hostages

Another paramount objective for Israel is the rescue or release of the roughly two-hundred Israeli, American, and other foreign hostages. Hamas’s taking of hostages from Israeli territory and using them, illegally, as human shields in Gaza under life-imperiling conditions pose particular challenges for Israeli military action. If Hamas had not taken hostages, Israel’s strategy for confronting the militant group might have been different.

Though much debated among international lawyers and governments, there is a legal right [PDF] for states to use force to rescue hostages, as long as their actions meet four criteria:

• many hostages are seized, particularly during an armed attack (as occurred on October 7),
• the actions are necessary (there is a threat of violence against Hamas’s hostages, and non-forcible recovery options, such as a negotiated deal with the group, may prove futile),
• there is an immediacy (a quickly negotiated release is not possible, and the fate of the hostages appears to worsen with each passing day), and
• the use of force is proportional (using only the level of armed force that is necessary to rescue the hostages).

The final criterion of proportionality would be superseded by the anticipated Israeli incursion into Gaza because that intervention would be made under the right of self-defense—a much larger-scale objective—and not only to rescue the hostages.

Whatever the debate may be about Palestinian statehood, the applicability of various treaties, and whether Israel is an occupying power over Gaza, Israel should take care to follow the powerful requirements of customary international law as it defends itself against Hamas and pursues the rescue of hostages.