The Catholic Church developed just-war theory, but the pontiff doesn’t seem to understand it.
By David B. Rivkin and Peter Berkowitz
December 13, 2023, in the Wall Street Journal
Pope Francis reportedly warned Israeli President Isaac Herzog in a phone call that it is “forbidden to respond to terror with terror.” Assuming he meant this as a criticism of Israel’s efforts to defend itself against Hamas, one might dismiss it as the ill-informed opinion of a left-leaning politician. But the pope’s error is worth taking seriously, because he speaks with some authority on matters of war and peace. Catholic theology has shaped the Judeo-Christian “just war” theory that midwifed the modern laws of war.
If the pope believes there is a certain level of civilian casualties in Gaza that is per se impermissible, he is fundamentally wrong. That view, common though it is, conflicts with key just-war precepts that demand careful balancing of competing imperatives.
Just-war doctrine, while refined over the centuries, was largely developed within the Christian tradition by St. Augustine of Hippo in the fourth century. Augustine rejected primitive Christian pacifism and argued that war, waged in compliance with proper rules, is a necessary tool of ethical statecraft. Acknowledging the sanctity of human life and expressing concern about the harm inevitably caused by a clash of arms, just war’s principal role is to protect the innocent to the extent possible, a task that pacifism can’t accomplish.
Just-war precepts, as incorporated into the traditional laws of war, have two distinct components. The first, jus ad bellum, comprises the rules governing when force may be rightly used. These include just cause, legitimate authority, public declaration, proper intent, proportionality, use of arms as the last resort, and reasonable hope for success. Given Hamas’s longstanding resolve to destroy the Jewish state, the failure of several Israeli military campaigns over the years to deter the terror group, and the Oct. 7 massacre, Israel unquestionably meets these criteria.
The second component, jus in bello, encompasses the rules governing how force may be lawfully used, including at whom it may be directed. This component underwent considerable doctrinal refinement between the 17th and 19th centuries. On April 24, 1863, the U.S. became the first military power to promulgate a comprehensive jus in bello manual, known as the Lieber Code.
Combatants must comply with both jus in bello and jus ad bellum, and violations by one side don’t justify violations by the other. Yet defining a war crime isn’t a simple matter of counting bodies. The weighing of conflicting imperatives permeates every facet of just-war theory. Guiding this balancing is the principle of double effect, which holds that it is morally permissible to act in pursuit of a good goal even if doing so would produce unintended but foreseeable harm. This principle is undergirded by a broad proportionality requirement, which measures the totality of positive and negative consequences of prosecuting a given war.
Jus in bello law contains two basic principles. The principle of discrimination forbids deliberate attacks on civilians and civilian infrastructure. It is absolute and brooks no departures. The principle of proportionality holds that in attacking legitimate military targets—which include military facilities that Hamas has integrated into civilian infrastructure—combatants are permitted to cause unavoidable collateral damage to civilians and civilian infrastructure, provided the harm is proportional to the value of the legitimate military objectives being sought. Destroying Hamas qualifies as a paramount military objective.
The principle of proportionality has been traditionally applied with considerable flexibility, in part because balancing its imperatives depends on combat circumstances that involve complex technical matters that are inherently difficult to gauge.
The laws of war used to play no favorites. Since World War II, however, humanitarian organizations, led by the International Committee of the Red Cross, have sought to provide special privileges for national liberation movements, an imprecise term that could include Hamas. These organizations have also tried to dilute rules that classify as unlawful enemy combatants fighters who don’t bear arms openly, don’t wear distinctive uniforms, and don’t operate in military organizations that feature well-defined command structures. Those efforts have constrained the military flexibility of law-abiding powers.
Equating unintended and proportional collateral damage with terrorism, as Pope Francis apparently did, goes further. It undermines the right to self-defense, the cornerstone of the laws of war. If the characterization of Israel’s exercise of its right of self-defense as terrorism were to prevail, the laws of war, instead of reflecting the military imperatives of law-abiding powers, would give a decisive advantage to terrorists and rogue states.
This is particularly dangerous at a time when Hamas jihadists commit horrific war crimes and Russia attacks, tortures and rapes civilians and brutalizes prisoners of war. For rogue entities like these, war crimes aren’t a cruel aberration but an integral part of their battle plans.
The pope’s comments to Mr. Herzog amount to a rejection of just-war theory and an embrace of primitive pacifism. They fail to understand that what happens in Gaza won’t stay in Gaza. If the laws of war were rewritten to preclude law-abiding powers like Israel and the U.S. from defending themselves against lawless combatants like Hamas, Hezbollah and Iran, lawlessness would inevitably prevail.
Mr. Rivkin practices appellate and constitutional law in Washington. He served at the Justice Department and the White House Counsel’s Office in the Reagan and George H.W. Bush administrations. Mr. Berkowitz is a senior fellow at Stanford’s Hoover Institution. He served as director of the U.S. State Department’s policy planning staff, 2019-21.