Pundits of all stripes are tearing into one another right now about how to interpret international law. Hamas has indubitably broken it in the worst possible ways. But is Israel doing so as well? As political as it is legal, that controversy raises an older question: What is international law, and does it even exist?

There’s no question that Hamas committed heinous war crimes on Oct. 7, when it attacked Israel and sadistically slaughtered about 1,200 people, mostly civilians. It broke additional international laws when it took civilian hostages, and yet more when it started using 2 million Gazan civilians as human shields. All of these acts are illegal in both customary and treaty-based international law.

As for Israel, the victim nation, international law expressly gives it the “right to war” (jus ad bellum) in self-defense. But it also governs how it must fight “in war” (jus in bello). Here, the legal reasoning is clear in theory but slippery in practice. Israel must do its utmost to spare civilians, for example, although legitimate military objectives may justify some civilian deaths, as long as the toll is “proportionate.” Is a Gazan body count of 11,000-and-counting proportionate?

Moreover, international law prohibits collective punishment. Is that what Israel exacted when it turned off water, fuel and electricity to the entire Gaza Strip? Israel says no. Others say yes, and point to comments like the Israeli defense minister’s, who, in ordering “a complete siege on the Gaza Strip,” added that “we are fighting human animals and we are acting accordingly.” Prime Minister Benjamin Netanyahu ominously cited Deuteronomy 25:19, where God tells the Israelites to “blot out the name of Amalak from under heaven.” Are the Gazans today’s Amalekites?

Ambiguity in international law is one thing; ambiguity about who would even enforce it, and how, is another. That becomes clear in a different context, concerning Russian President Vladimir Putin. He broke a cardinal rule of international law when his troops invaded a sovereign country, Ukraine. But the United Nations has done little – because Russia holds a veto on its Security Council.

Putin’s troops then committed additional atrocities, from maiming, torturing, raping and murdering Ukrainian soldiers and civilians to abducting their children, which is part of the definition of genocide. For that latter crime, the International Criminal Court in the Hague – established by the Rome Statute of 1998, a crown jewel of international law – has issued an arrest warrant against Putin and another Russian leader.


But neither Russia nor Ukraine is a party to the Rome Statute. (Nor is the U.S., China or Israel, for that matter, although Palestine is.) As long as Putin doesn’t set foot in one of the 123 signatory nations, and arguably even if he does, he therefore won’t, in any plausible scenario, get arrested.

The apparent impunity of perpetrators like Putin raises the bigger question hanging over international law: whether it is in fact “law” at all. Thinkers from Thomas Hobbes to Hans Morgenthau stipulated that law only deserves that label when it can be enforced. The enforcer, moreover, needs what the sociologist Max Weber called a monopoly on legitimate violence. Typically that means a national government, which can legally arrest, incarcerate, expropriate or even kill.

But there is no corresponding world government, and hence no international body with a monopoly on legitimate violence. The global system is therefore said to be an “anarchical society.” To some legal philosophers, international law is thus little more than “positive morality,” a set of norms and suggestions, easily ignored and unenforceable.

Others throughout the ages, however, have felt that something is missing in that analysis. The greatest thinker in that tradition was Hugo Grotius, a 17th century Dutch humanist and polymath who once smuggled himself out of prison by hiding in a bookcase and survived a shipwreck.

Grotius lived during the Thirty Years War, when more than 60% of the population in some parts of Central Europe perished. Europe’s great powers as well as private armies did the slaughtering, and there was nothing to restrain them. As an intellectual – and later as ambassador from one belligerent, Sweden, to another, France – Grotius helped conceive the modern states’ system that would emerge from this bloodbath.

Along the way, Grotius also developed the foundational texts of international law, from rules governing ocean navigation (which live on in the U.N. Convention on the High Seas) to the norms of going to war, and then of waging it – that is, the jus ad bellum and the jus in bello. To Grotius and his heirs, international law was part of natural law, the way things just ought to be.


In the centuries since, a body of customary international law developed, based on precedent and analogous to case law in common-law countries. On top of that are treaties, conventions and agreements, the equivalent of statutes in national law. Starting in the 19th century and into the 20th, the International Committee of the Red Cross pushed international humanitarian law in particular (a modern synonym for jus in bello) and helped birth the Geneva Conventions and its protocols. The Charter of the United Nations and conventions on everything from trade to labor standards and space exploration round out the system.

International law is thus both ubiquitous and indispensable. It works best during peacetime, when countries feel most bound by reciprocity – I won’t drill for oil on your continental shelf, as long as you don’t drill on mine. But once countries or leaders feel that vital interests are at stake, and especially once they go to war, they often ignore the law, as Putin does. (That said, he did skip a summit in South Africa, which is a signatory to the ICC – perhaps he was nervous about getting arrested after all.)

However imperfect, though, international law makes life for many people less nasty, brutish and short than it would otherwise be – than it was during the Thirty Years War, say. It restrains combatants by separating the why of war from the how – as Charli Carpenter at the University of Massachusetts-Amherst puts it, by distinguishing “between ‘civilized’ violence and outright barbarity.” It gives moderates in every society a language in which to address and temper the bloodthirsty in their own ranks and to hold them individually accountable after the guns fall silent. It maintains norms of humanity.

You may lean Hobbesian or Grotian, realist or idealist. You may doubt international law is even a thing or swear by it. You may think it is failing in the Gaza Strip or preventing even worse suffering. But let us be grateful that international law exists, for the alternative is worse. That’s enough reason to defend it.

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