“The Constitution is not a suicide pact,” wrote Supreme Court Justice Robert H. Jackson in 1949. He was right. Even though there is no provision in our Supreme Law saying so, it is inherent, if unstated, in every law. We cannot interpret the Constitution—or any law—in such a way that sows the seeds of its destruction. The Constitution exists to constitute a nation, just as a law exists to govern those within its jurisdiction. If one provision were to lead to the destruction of those committed to abiding by the law, either by crowding out all other laws or commanding an untenable outcome, the whole purpose of having law in the first place would be defeated.

　　The Jewish tradition includes similar teachings, with the caveat that all but three commandments may be broken in order to save a life. “Keep my laws and my commandments,” reads Leviticus, “that man can perform and live by them.” The sages of the Talmud added a gloss: “Live by them, and do not die by them.” Law, even divine law, is for the living. It cannot counsel outcomes that would prevent further performance of commandments.

　　Of all systems of law or norms, the law of armed conflict (LOAC, or rules of war) must share this feature. LOAC, and the theories of just war that undergird it, is uniquely susceptible to becoming a suicide pact because it is only applied, to state the obvious, during armed conflicts. If LOAC restrains its adherents to such a degree or in such a way as to make winning a war impossible—to put law-abiding nations at risk of collective suicide—it will have rendered the idea of a “just war” null. Nations sympathetic to LOAC would justifiably abandon it before it could undermine their survival, or LOAC would be phased out of existence as adherent nations succumb to its demands and the unscrupulous enemies who do not consider themselves so restrained.

　　This all seems quite obvious in the abstract, and one suspects that Michael Walzer, widely considered the leading light of just-war theory, would agree that none of this is controversial. He has said so in slightly different language: “It is a central principle of just-war theory that the self-defense of a people or a country cannot be made morally impossible.” Indeed, if the cause of a war is just, there must be a way to execute its aims. It is hard to square these truisms, however, with Walzer’s recent New York Times essay condemning Israel’s exploding-pager-and-walkie-talkie attacks on Hezbollah as “very likely war crimes.”

　　Walzer’s take was quite simple. He did not stretch, as some anti-Israel ideologues posing as humanitarians did, to accuse Israel of booby-trapping military devices. “Yes,” he conceded, “the devices most probably were being used by Hezbollah operatives for military purposes. This might make them a legitimate target in the continuous cross-border battles between Israel and Hezbollah.” By contrast, Kenneth Roth, the former head of Human Rights Watch, rationalized his opprobrium for Israel by calling Hezbollah-issued communications devices “objects that civilians are likely to be attracted to or are associated with normal civilian daily use.”

　　However, writes Walzer, “the attacks,” which detonated a small amount of explosives in these devices, and appears to have blown limbs and appendages off thousands of individuals possessing them, “came when the operatives were not operating; they had not been mobilized and they were not militarily engaged. Rather, they were at home with their families, sitting in cafes, shopping in food markets—among civilians who were randomly killed and injured.”

　　This is a puzzling element of just-war theory that warrants some elaboration. Some questions, which a military interested in following LOAC would want answered, spring to mind: What counts as “militarily engaged”? Do the people who were checking their pagers and walkie-talkies to receive mobilization instructions count as “mobilized”? Should combatants in an active war—or, to grant Walzer’s understatement of the last year’s developments, in which Hezbollah has launched over 8,000 missiles at Israeli towns, forcing mass evacuations and drawing an Israeli response that has already killed hundreds of Hezbollah fighters, “cross-border battles”—be granted full safe harbor when surrounded by civilians?

　　Interestingly, Walzer does not fill out the details of the distinction on which his criticism hinges. Instead, he slips almost immediately into a different analysis altogether. “The theory of just war depends heavily on the distinction between combatants and civilians, he writes, and “a military responding to this strategy,” of deliberately mixing combatants and civilians in the same space, “has to do everything it can to avoid or minimize civilian casualties.” This is a classic proportionality argument. Proportionality demands that an attack only harm civilians to the extent necessary to achieve its legitimate military ends. The question, then, is whether the number of injured and killed civilians “outweighs”—this is both a tragic and impossible calculation—the value of disarming and dismembering Hezbollah fighters. It is highly debatable, as Walzer knows well. As he wrote in 2009, “Anyone who thinks this is an exact science needs to be reminded that the calculations are necessarily rough and the numbers [of fighters “worth” civilian lives] always contestable.” But it certainly has nothing to do with whether Hezbollah fighters are “militarily engaged.”

　　So, how are we to answer the questions Walzer’s criticism necessarily raises? Perhaps we can enter the analysis by pondering what it means to be “militarily engaged.” One can certainly draw lines about when enemy fighters present a clear and present danger sufficient to justify a strike that may harm civilians. Perhaps picking up a deadly weapon indicates sufficient engagement to act in self-defense; maybe Israel should wait until every gun is cocked and every rocket launcher is loaded, aimed, and ready to fire. But these are arbitrary and seem to impose enormous costs on the party that is trying to do the right thing while increasing the chances that the bad guys succeed. No nation would abide by a rule that required forbearance until the last possible second—nor should we expect it to.

　　“Militarily engaged” is not a useful concept; to breathe life into it in any workable way is to write it out of just-war theory entirely.

　　A better standard is one Walzer endorsed in the past: “We can kill enemy soldiers even if they are far from the battlefield.” This is especially true in warfare that does not quite have a battlefield and is instead conducted largely by launching missiles from sites scattered throughout a country, including densely populated urban areas. Drone attacks, which have become a staple of Hezbollah sorties, are even more dramatic examples of the decentralization of contemporary warfare; they can be directed and detonated from anywhere. In modern warfare, militarily engaged means being an enemy combatant in an active war. Hezbollah fighters cannot turn that status on and off at will. They can cease their unjust war against Israel if they no longer wish to die.

　　Israel would thus be justified in killing members of Hezbollah regardless of where they are, within the limitations imposed by the proportionality principle. As applied to the daring pager/walkie-talkie strike, that means not rigging the pagers with more explosive material than is necessary to achieve the goal of killing the Hezbollah operative. That seems to have been achieved; if anything, given the numbers of non-fatal injuries to pager owners, Israel may have erred on the side of too little.

　　In other words, “militarily engaged” is not a useful concept; to breathe life into it in any workable way is to write it out of just-war theory entirely. This points to a fatal and inherent problem with the very distinction that constitutes Walzer’s criticism. It implies that, at least under certain circumstances, Hezbollah (and fellow terror organizations) can receive safe harbor by embedding in civilian populations, raising the civilian costs of otherwise potentially legitimate strikes. Here we go again. Systemic use of human shields is not limited to Hamas and Hezbollah, but those groups have made the most use of it, weaponizing their indifference to civilian life in Gaza and Lebanon, respectively, against Israel in the court of international opinion. They have largely succeeded in the West, as evident when Israel is blamed at all for civilian deaths—and even Israel’s self-styled defenders have chastised it to “do more” to avoid them—where terror organizations have launched wars and then hidden behind civilians. This is, as Walzer has pointed out in the past, perverse:

　　If the number of likely civilian deaths is always disproportionate to the value of destroying the rocket launcher and its operatives, or the cache of rockets, so that Israel would be prohibited from responding in any fashion to the rocket attacks, then the prohibition associated with counterattacking collapses. Now even “disproportionate” counterattacks are justified and, assuming the Israelis exercise the necessary care, responsibility for civilian deaths falls solely on Hezbollah and Hamas. … The more civilians are used as shields, the greater the danger to which they are exposed, and responsibility for that exposure falls on the people who are using them.

　　Yet today Walzer lends his credibility and the weight of just-war theory to the opposite position, by condemning an Israeli attack designed to harm combatants seeking refuge amongst civilians, while minimizing collateral harm.

　　If attacking non-engaged operatives is prohibited by just-war theory and LOAC, those venerable institutions will have met their death knell. Full blame and condemnation for civilian harm in Lebanon must fall on Hezbollah, which began a war with Israel on October 8, 2023, and commits the systematic war crime of embedding itself and its war materiel in civilian areas. If they are immune from counterattack—even “disproportionate counterattacks,” in Walzer’s previous words—under any categorical rule of time or place, the future of warfare will belong to those who are quickest to put themselves in those times and places. In other words, LOAC will be a gift to the unscrupulous actors, those with ill will, and those who do not care whether they harm civilians to achieve their war aims. The loophole will have swallowed the rule; the law will become a nullity as it restrains good actors and rewards evil ones.

　　Thankfully, Walzer is wrong. Israel’s precision attack conforms to the demands of just-war theory and LOAC by tailoring its violence ingeniously towards combatants, representing a remarkably precise alternative to airstrikes or a ground invasion. Israel can live by LOAC; it need not die by it. It could not be otherwise. After all, the law is not a suicide pact.