Proportionality in the Israel-Gaza Conflict: A Legal Primer

Posted in: International Law

Politicians, commentators, and the lay public across the political spectrum have spoken to whether the conflict in Israel and Gaza is proportionate. Many have used a 9/11 analogy, suggesting that Israel is empowered to do as much or more than the United States did in the wake of its own devastating terrorist attack. Others have pointed to the extensive casualties incurred during the war on terror as evidence that the U.S. response was disproportionate and thus Israel ought not follow the same path. To complete the spectrum, some have suggested that the U.S. response was proportionate but since Israel has used more bombs in the past three weeks than the U.S. used in the heaviest year of the war on terror, such a response is disproportionate.

I want to introduce two ways in which international law demands proportionality with regards to conflicts and two ways in which it prohibits considerations of proportionality. Of course, many of those who speak to proportionality in the Israel-Gaza conflict are speaking in moral terms rather than legal terms. But some seem to be mistaking or conflating what the law demands with what they think the law ought to be or the demands of morality or both. I think it useful to have an understanding of what international law permits and what it forbids before engaging in or assessing these debates. I want to reinforce that existing international law draws some dividing lines between lawful and unlawful actions, but leaves open some moral questions about what, if anything, ought to be considered lawful but awful.

In focusing on proportionality in attacks, I am leaving aside the intentional targeting of civilians.[1] Not because such activity is legally or morally permissible. I believe it to be reprehensible and properly outlawed. Rather, I think substantially less confusion exists as to whether such behavior is in fact lawful under the existing use of force law and international humanitarian law. While some do make the argument that killing civilians is morally permissible under the demands of resistance and/or that all accountability for such actions lies with those creating the conditions making resistance necessary, there does not seem to be much slippage between their moral viewpoints and their understanding of existing international law.

Proportionality as to Use of Force at All

The recourse to force at all and how much force overall is governed by what is termed jus ad bellum in international law. In other words, law speaks to the question of when and how much force is permissible in an armed conflict. For states, the U.N. Charter along with the inherent right of states to self-defense authorizes when force may be used at all. The October 7 attacks on Israel certainly constitutes an armed attack sufficient to invoke the right to self-defense. While some have characterized Israel as a colonizer or an apartheid state, neither characterizations, even if accepted as true, would deprive the state of its rights to self- defense under customary or treaty based international law.

What about the limits on resort to force for non-state actors? International law provides no general authorization for non-state actors to use force that would parallel a state’s right to self-defense. That said, the UN’s 1970 Declaration on Principles of International Law Concerning Friendly Relations and Cooperation Among States in Accordance with the Charter of the United Nations ambiguous wording leaves open the possibility that national liberation movements may use armed force to enforce the right to self-determination against those that have denied such right. Some states and scholars hold this view, but no clear consensus has emerged as to the legality of a national liberation movement’s right to resort to force and under what exact conditions.

In contrast, much doctrine and precedent speaks to the limits of a state’s invocation of the right to self-defense. For instance, the 1837 Caroline incident stands as precedent for the premise that states may use force in self-defense in response to an armed attack if that force satisfies proportionality (in addition to necessity and immediacy) in repelling the attack. This framework still governs today and thus the question of proportionality with regards to the right to self-defense is a live legal one. To answer it, under Caroline and its progeny, one must assess the amount of force necessary to deter or defeat the attack. Such an inquiry looks at the overall military goal as opposed to directly comparing the harm of the initial (or ongoing) attack(s) and the harm of the response.

So when asking about the overall proportionality of Israel’s response (as opposed to the proportionality of discrete uses of force such as bombing an apartment building), one should not rely on an apples-to-apples comparison of civilian casualties on each side, but rather whether Israel’s response is using necessary or excessive force to eliminate the danger that Hamas has and continues to present. So the legal question (as opposed to a political or moral one) is whether the amount of force used exceeds the need to eliminate the ongoing threat of Hamas. Answering such a question relies on addressing both sides of the ledger and assessing the threat as well as the force—something many of the contemporary discussions fail to do. This primer does not attempt to do the weighing, but rather to equip the reader with the framework within which to ask the relevant questions.

Proportionality Under the Laws of War—With an Emphasis on Attacks

A related, but legally distinct question is the question of proportionality as governed by the laws of war. The laws of war bypass questions about the legitimacy of recourse to force and instead govern parties as to their conduct during conflict. The laws of war embody four basic principles: military necessity, humanity, distinction, and proportionality. The “proportionality” principle of the laws of war is enshrined in numerous provisions within laws of wars treaties—most notably Articles 51(5) and 57(1) of the Additional Protocol I to the Geneva Convention. Those articles render an attack which may be expected to cause excessive loss of civilian lives as in relation to the concrete and direct military advantage as unlawfully indiscriminate and require that those engaging in attacks must take precautions to refrain from attacks that violate the aforementioned proportionality balancing. In other words, the military advantage must outweigh the anticipated civilian losses in order to be lawful.

The laws of war rely on status categorizations to determine whether and how individuals are balanced for purposes of proportionality analysis. The categories of combatants and “civilians directly participating in hostilities” for such time as they are participating do not factor into proportionality analysis. For example, if one side plans an attack to destroy a military base, they would need to balance for any civilians present on base, but would not have to consider the harms against opposing combatants (or civilians directly participating in hostilities). There is no such thing as excess combatant casualties for purposes of the laws of war. In contrast, civilians (not directly participating in hostilities) must be considered in the proportionality analysis. Given this, parties are neither allowed to use civilians to render military objectives off limits (i.e., human shields) nor are parties allowed to ignore such individuals should they be co-located with military objectives.

Even within a strict classification system, hard questions still arise. For instance, how should the laws of war account for those who willingly protect military objectives but do not otherwise participate in hostilities? Scholars still actively debate whether voluntary human shields ought to be counted as: (1) civilians directly participating in hostilities in which case they are irrelevant to the proportionality analysis; (2) civilians who remain protected from attacks and must be fully counted in the proportionality analysis; (3) civilians who remain protected from attacks but may be discounted somewhat in the proportionality analysis.

But there are some easy answers provided by the laws of war proportionality principle as well. Laws of war proportionality does not require parity of civilian casualties across parties nor does it even permit balancing of civilian casualties across parties as part of the legal calculation. In other words, the number of civilian casualties on one side does not inform whether a substantially larger number of civilian casualties on the other side is disproportionate under the laws of war. Nor does the laws of war permit proportionality balancing based on the “justness” of a side’s reason for engaging in armed conflict. Neither self-defense nor efforts to enforce the right to self-determination nor any other justification offered in this current conflict allow participants to add change the inputs or the weights assigned to the considerations in the proportionality analysis. They are limited to the direct and concrete anticipated military advantage on one side and the anticipated civilian losses on the other side.

Nor do the laws of war permit retaliation against civilians. Tit-for-tat attacks on civilians violate civilians’ immunity from attack. While they might seem like parity, they are not proportionate as understood by the laws of war. While international law does sometimes permit countermeasures to encourage compliance by those who have engaged in internationally wrongful acts, Article 51 of the 1977 Additional Protocol I clearly prohibits reprisals undertaken against civilian populations (though there is some debate as to whether that reflects customary international law). For adherents to this view,one may not attack civilians and claim proportionality even if they can point to a prior incident of the other side engaging in civilian targeting or imposing disproportionate civilian losses. States may not target civilian populations or disregard proportionality analysis even in response to opposing forces that flagrantly violate the laws of war.


So what then, legally ought one to make of the reported 7,000 Palestinian civilian casualties? Given those numbers, it’s understandable why the public might be skeptical of those saying Israel is compliant, but it’s also understandable why states might be skeptical of the alleged civilian death toll. Reported high civilian casualties ought to give rise to significant concern and public inquiry. The number is certainly relevant, but it is a starting point rather than an endpoint. Under laws of war proportionality analysis, one must break down specific attacks and determine first how to identify and classify all the casualties. Then, one must also account for Israel’s military objectives and their weightiness and then determine the anticipated civilian casualties. Of course, that kind of analysis is quite difficult and often out of reach for the lay public., Hence, as I argued in the war on terror and as I hope to develop in a future post, if we want to get a better grasp on whether proportionality is being satisfied, we need some transparency as to how military objectives are chosen, access to standards for how individuals status is determined, and how proportionality analysis is conducted as well as external investigations.

[1] Given the specific rules governing sieges and space constraints, I am also leaving aside the siege and how it affects access to resources like water and food. For an excellent discussion of how the laws of war apply to the siege with specific respect to the prohibitions against starving civilians, see Rosa-Lena Lauterbach’s post at Articles of War.

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