Editor’s note: Just Security has published a response to this article (here) and a reply by Professor Adil Haque (here).

At the United Nations Security Council, States from every region of the world condemned Israel’s use of force in Gaza as disproportionate and called for it to end. These States included Belgium, France, Iceland, Lithuania, Luxembourg, Norway, and the United Kingdom. They included Argentina, Bolivia, Brazil, Ecuador, and El Salvador, Paraguay, and all other members of MERCOSUR. They included Bangladesh, Chad, Egypt, Jordan, Indonesia, Malaysia, Namibia, Pakistan, and South Africa. The European Union “condemn[ed] the loss of hundreds of civilian lives, among them many women and children,” “underline[d] that the Israeli military operation must be proportionate,” and “call[ed] on all sides to implement an immediate ceasefire in good faith.”

That was in 2009. And in 2014. But when the Security Council met a few weeks ago, to consider a draft resolution calling for a mere “humanitarian pause” in Gaza, States did not discuss whether Israel’s use of force was proportionate, or disproportionate, as a whole. They did not ask whether Israel’s war aims justify the killing of thousands, the wounding of tens of thousands, or the immiseration of millions. The question was never squarely raised.

Today, the Council seems divided into two groups. One group affirms Israel’s right of self-defense against Hamas, triggered by the mass murder of hundreds of Israeli civilians and the taking of civilian hostages, but calls on Israel to exercise that right within the limits of international humanitarian law (France, United Kingdom). The other group denies that Israel’s right of self-defense is engaged at all. Some in this group believe that the right of self-defense does not apply to the use of force against non-State actors, and that Hamas, despite its State-like features, remains a non-State actor (Brazil, see also here). Others in this group believe that the right of self-defense does not apply to armed groups emerging from occupied territory, and that Gaza remains under Israeli occupation (Jordan, Pakistan). These States also insist that Israel must respect IHL. On that, all agree.

I believe in international humanitarian law. I believe that the war in Gaza would be even worse without IHL, and I believe that IHL gives us an important tool to save lives as long as the fighting goes on. But the fighting must stop. Hamas and Israel must accept a ceasefire. They must then end their many other ongoing violations of international law. Hamas must release all its hostages. Israel must allow and facilitate rapid and unimpeded humanitarian relief. I could go on. And on.

As of now, it appears that Israel will not accept a ceasefire, even if Hamas stops firing rockets and releases all its hostages, because Israel’s stated war aim is to destroy Hamas as a military and political organization, in light of the group’s intent and capacity for further attacks. If Israel pursues this war aim until it is achieved, or until it proves impossible to achieve, then there is only so much that IHL can do to limit the total number of Palestinian civilians that the Israeli military will kill, maim, and dispossess.

Under IHL, proportionality applies to specific attacks, comparing expected civilian harm with anticipated military advantage. It takes war aims more or less as given. It asks how much a specific attack will contribute to the achievement of these aims, and at what cost.

In contrast, proportionality in the exercise of self-defense applies to the military campaign as a whole, “assessing whether the harmful effects of the force taken in self-defence are outweighed by achieving the legitimate aims.” (ILA Use of Force Committee, Final Report on Aggression and the Use of Force (2018)).

Under the law of self-defense, even a legitimate aim must be set aside if it is outweighed by the harmful effects of the force necessary to achieve it. Even if Israel’s right of self-defense is engaged, its current exercise of that right is disproportionate. Israel must either accept an immediate ceasefire, or drastically narrow its war aims and dramatically change its tactics. If Hamas stops firing rockets and releases its hostages, then the war must end there. Israel may not continue to fight until Hamas is destroyed and another three thousand children are dead.

This is the stance I would advise for those States that affirm Israel’s right of self-defense while calling for a ceasefire. As it stands, their position is morally compelling but legally incomplete. We are all familiar with legal rights to commit moral wrongs. It is perfectly coherent to say that Israel has a legal right to pursue Hamas’s total destruction, but that it would be morally wrong to do so in light of the total harm that it would inflict on civilians. Nevertheless, the position of these States would be stronger if they rest it on legal as well as moral grounds. Since the United States is likely to veto any Security Council resolution calling for a ceasefire, it is important to show that Israel is legally obligated to accept a ceasefire with or without such a resolution.

Some States outside the Council have emphasized that Israel’s right of self-defense is limited by principles of necessity and proportionality. Norway has gone further, indicating that Israel’s siege tactics are unnecessary and disproportionate, as well as violations of international humanitarian law. Norway’s prime minister, Jonas Gahr Støre, went still further, saying that “we defend Israel’s right to defend itself. … At the same time, we require that proportionality is respected. And the extent of destruction and the humanitarian suffering happening now [in Gaza] is beyond that.” Norway was one of the first European States to call for a ceasefire, and its invocation of proportionality supports this call.

I would also commend this approach as an argument in the alternative for those States that deny that Israel’s right of self-defense applies to the current conflict. I am inclined to agree with them, but it would not compromise any legal principle to say that even if the right of self-defense applied, Israel’s use of force would be disproportionate. Some of these States have said as much in the past, while preserving their more fundamental objections (Brazil, Jordan, Pakistan). This approach will allow States to reach a working consensus on disproportionality while bracketing their deeper disagreements over the preconditions of self-defense.

In discussions of self-defense, some States and scholars argue that proportionality limits armed force to the kind and degree required to repel an attack, but does not require any proportion between civilian harm and defensive benefit. The current conflict illustrates the folly of focusing only on the relation of defensive means and defensive ends while ignoring the relation between defensive ends and human costs. The best evidence that most States reject a purely instrumental conception of proportionality comes from prior Israeli bombardments of Gaza and Lebanon. On these occasions, States from every region of the world condemned Israel’s overall use of force as disproportionate in light of the total harm it inflicted on civilians. They should do so again.

It is not necessary to lay out a formula for weighing civilian harm and defensive benefit to apply in all future cases. There are reasonable debates to be had about how to compare death and injury, and whether to consider less tangible interests of individuals, communities, or States as such. States need not resolve those questions today, because the imbalance between the harm Israel will inflict and the harm Israel will prevent if it continues down its current path is so lopsided that it cannot plausibly be considered proportionate. For now, States only need to apply a general standard to reach a specific result.

One might argue, instead, that the total destruction of Hamas is not a legitimate defensive aim at all, that States have a legal right only to halt and repel an ongoing attack, and perhaps to prevent an imminent one. Even if the adversary has proven its intent and capacity to carry out future attacks, it is not lawful to pursue their total destruction. I might argue that myself. But my aim here is to identify a stance that many States can take right here, right now, namely that a State may not destroy an adversary’s capacity to launch future attacks at grossly disproportionate cost to civilians, whether or not this aim is legitimate in the first place. Indeed, some States might adopt a hybrid position: that a State may use as much force as necessary to halt and repel an ongoing armed attack, but may not eliminate the possibility of future attacks at disproportionate cost to civilians. Any of these permutations leads to the same result: that no State may inflict unlimited harm to achieve total security.

Hamas’s attack on October 7 was unprecedented in its scale and brutality, and it should never be allowed to reoccur. Israel’s ongoing military campaign is unprecedented in its scale and brutality, and it should not be allowed to continue. Israel must find a way to protect its citizens without unlawfully killing its neighbors.

Palestinians and Israelis are, first and foremost, human beings. We must ask whether the mass killing of one set of human beings is a proportionate means of completely protecting another set of human beings from all future threats. It is not. And for that reason, among many others, this war must end.

IMAGE: Members of the United Nations Security Council listen as Palestinian Permanent Observer Riyad H. Mansour speaks during a Security Council meeting on the Israel-Hamas war at U.N. headquarters on October 30, 2023 in New York City. (Photo by Michael M. Santiago/Getty Images)