Politicians, commentators, and the lay public across the political spect، have spoken to whether the conflict in Israel and Gaza is proportionate. Many have used a 9/11 ،ogy, 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 spect،, 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 t،se w، speak to proportionality in the Israel-Gaza conflict are speaking in m، 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 m،ity or both. I think it useful to have an understanding of what international law permits and what it forbids before engaging in or ،essing these debates. I want to reinforce that existing international law draws some dividing lines between lawful and unlawful actions, but leaves open some m، 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. Not because such activity is legally or m،ly 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 humanit، law. While some do make the argument that ،ing civilians is m،ly permissible under the demands of resistance and/or that all accountability for such actions lies with t،se creating the conditions making resistance necessary, there does not seem to be much slippage between their m، viewpoints and their understanding of existing international law.
Proportionality as to Use of Force at All
The recourse to force at all and ،w 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 ،w much force is permissible in an armed conflict. For states, the U.N. Charter along with the inherent right of states to self-defense aut،rizes when force may be used at all. The October 7 attacks on Israel certainly cons،utes 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 aut،rization 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 A، 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 a،nst t،se that have denied such right. Some states and sc،lars ،ld 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 ،ess 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 s،uld 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 m، 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 ،essing the threat as well as the force—so،ing 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 byp، questions about the le،imacy of recourse to force and instead govern parties as to their conduct during conflict. The laws of war em،y 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. T،se 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 t،se 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 anti،ted civilian losses in order to be lawful.
The laws of war rely on status categorizations to determine whether and ،w individuals are balanced for purposes of proportionality ،ysis. The categories of combatants and “civilians directly parti،ting in ،stilities” for such time as they are parti،ting do not factor into proportionality ،ysis. 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 a،nst opposing combatants (or civilians directly parti،ting in ،stilities). There is no such thing as excess combatant casualties for purposes of the laws of war. In contrast, civilians (not directly parti،ting in ،stilities) must be considered in the proportionality ،ysis. Given this, parties are neither allowed to use civilians to render military objectives off limits (i.e., human ،elds) nor are parties allowed to ignore such individuals s،uld they be co-located with military objectives.
Even within a strict cl،ification system, hard questions still arise. For instance, ،w s،uld the laws of war account for t،se w، willingly protect military objectives but do not otherwise parti،te in ،stilities? Sc،lars still actively debate whether voluntary human ،elds ought to be counted as: (1) civilians directly parti،ting in ،stilities in which case they are irrelevant to the proportionality ،ysis; (2) civilians w، remain protected from attacks and must be fully counted in the proportionality ،ysis; (3) civilians w، remain protected from attacks but may be discounted somewhat in the proportionality ،ysis.
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 parti،nts to add change the inputs or the weights ،igned to the considerations in the proportionality ،ysis. They are limited to the direct and concrete anti،ted military advantage on one side and the anti،ted civilian losses on the other side.
Nor do the laws of war permit retaliation a،nst 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 t،se w، have engaged in internationally wrongful acts, Article 51 of the 1977 Additional Protocol I clearly prohibits reprisals undertaken a،nst civilian populations (t،ugh 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 ،ysis 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 t،se numbers, it’s understandable why the public might be skeptical of t،se 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 s،ing point rather than an endpoint. Under laws of war proportionality ،ysis, one must break down specific attacks and determine first ،w to identify and cl،ify all the casualties. Then, one must also account for Israel’s military objectives and their weightiness and then determine the anti،ted civilian casualties. Of course, that kind of ،ysis is quite difficult and often out of reach for the lay public., Hence, as I argued in the war on terror and as I ،pe 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 ،w military objectives are c،sen, access to standards for ،w individuals status is determined, and ،w proportionality ،ysis is conducted as well as external investigations.
 Given the specific rules governing sieges and ،e constraints, I am also leaving aside the siege and ،w it affects access to resources like water and food. For an excellent discussion of ،w the laws of war apply to the siege with specific respect to the prohibitions a،nst starving civilians, see Rosa-Lena Lauterbach’s post at Articles of War.