The Moral Disorder of Jus ad Bellum and Jus in Bello Purity

In my last post, I argued why the law of armed conflict (LOAC) does not require the absolute separation of jus in bello and jus ad bellum. I also identified how leading thinkers throughout history understood the two to be inextricably, fundamentally linked, until very recently.

Here, I argue that prevailing constructions of LOAC, which commonly hold that jus in bello and jus ad bellum are hermetically sealed off from each other, are disordered because they purport to elevate abstract humanitarian universality above the fundamental right of political communities to survive.

The argument is straightforward. First, as agents of their sovereign people, States have a constitutive right to self-preservation which they cannot alienate, even via treaty. Second, any interpretation of a treaty obligation that demands suicidal restraint is, even within LOAC, ultra vires any State authority. No State has the competence to consent to its own political destruction. It follows, therefore, that LOAC’s most restrictive provisions—those whose observance would otherwise entail self-destruction—can operate fully only against unjust aggressors, not defending States. Otherwise, compliance negates the defending State’s political survival.

Sovereign Duty and the Inalienable Right to Self-Preservation

At the heart of the debate over whether jus in bello and jus ad bellum should be kept absolutely separate is the underlying question of LOAC’s role vis-à-vis a sovereign’s duty. That is, when all other avenues are closed, can LOAC require a party fighting for a just cause to yield to an adversary fighting in furtherance of an unjust cause? Or is there a threshold at which jus ad bellum concerns may “override” LOAC’s restrictions?

Some scholars have concluded that a State’s reason for going to war can never override its obligations under LOAC. “[T]here is no basis in international law for introducing the notion of the survival of the state as a legitimate excuse for violating the law of armed conflict,” concluded one scholar. “In short, the maxim that Not kennt kein Gebot (‘necessity knows no law’) ‘finds no place in jus in bello,’” wrote another. Indeed, in the International Court of Justice (ICJ)’s Nuclear Weapons advisory opinion, several States—including Egypt, Mexico, and the Solomon Islands—argued that the principles of LOAC are jus cogens, absolute, and brook no exceptions, even for reasons of State survival or necessity.

The chief problem with these arguments is that they reflect an improper ordering of human affairs. States do not go to war to practice LOAC, just as they do not exist to serve a rules-based international order. Similarly, people do not form nations (and eventually, a State) to realize their purpose of “finding a place” in legal regimes like jus in bello. Rather, it is jus in bello that must find its place in necessity.

Classically, a sovereign’s foremost duty, carried out through the State, has been to provide for the common defense. “[A nation’s] duties towards others depend very much on its duties towards itself, as the former are to be regulated and measured by the latter,” wrote Vattel in The Law of Nations (emphasis added). And because a nation exists only by a compact of voluntary association of individuals “to promote the general welfare” and protect its members, as Vattel wrote, barring explicit consent of those parties to the compact, it cannot abrogate this solemn duty of protection by way of international agreement. Thus, “a nation has a right to everything necessary for its preservation.”

Furthermore, this right is inalienable. Even if it wanted to, a State cannot “contract” away its claim to self-preservation any more than an individual can alienate the right to his or her life. Says Vattel (p. 213):

Since, in the formation of every treaty, the contracting parties must be vested with sufficient powers for the purpose, a treaty pernicious to the state is null, and not at all obligatory, as no conductor of a nation has the power to enter into engagements to do such things as are capable of destroying the state, for whose safety the government is intrusted to him. The nation itself, being necessarily obliged to perform everything required for its preservation and safety … cannot enter into engagements contrary to its indispensable obligations.

John Locke’s Second Treatise of Government says largely the same (“For a man, not having the power of his own life, cannot by compact or his own consent enslave himself to any one, nor put himself under the absolute, arbitrary power of another to take away his life when he pleases.”). As does Thomas Hobbes (“A covenant not to defend myself from force, by force, is always void. … [N]o man can transfer or lay down his right to save himself from death, wounds, and imprisonment…”) (Leviathan, p. 86). More broadly, Samuel von Pufendorf supports the same conclusion, albeit indirectly, holding that promises cannot bind where the promised act is forbidden by natural law, even with the consent of the affected party (“[W]e cannot be bound to perform anything unlawful … . [P]romises which will be injurious to him for whom they are made, ought not to be kept; since it is forbidden by the natural law to cause harm to another, even if he foolishly desires it”) (De Officio Hominis Et Civis Juxta Legem Naturalem Libri Duo, p. 45).

Of course, an individual (like a State) can choose not to exercise that right—even unto death—but such a choice does nothing to negate the supremacy of one’s claim to one’s life over all other claims to the same life. In fact, it reinforces that supremacy.

As to this right of self-preservation, Vattel is likewise not alone in his thinking. For example, Henry Wheaton’s 1866 treatise, Elements of International Law states, “Of the absolute international rights of States, one of the most essential and important, and that which lies at the foundation of all the rest, is the right of self-preservation” (§ 61) (emphasis added). Walzer’s concept of supreme emergency also comes to mind (see Just and Unjust Wars, p. 250). So, too, does Locke, which holds that “[t]he great and chief end … of men’s uniting into commonwealths, and putting themselves under government, is the preservation of their property.” Importantly, Locke understood “property” to encompass a person’s life and means for survival, a point that becomes particularly relevant considering his views on sovereign legitimacy later on (that is, a people are “absolved any farther obedience” to legislators that “put themselves into a state of war with the people,” whereupon the people are “left to the common refuge, which God hath provided for all men, against force and violence”).

Before Locke, Hugo Grotius, although often credited as the author of the separation (but not total separation) of jus in bello and jus ad bellum in De Jure Belli ac Pacis, centered self-preservation as our foremost natural duty. He says, “[P]reserving ourselves in a natural state, and holding to every thing conformable, and averting every thing repugnant to nature is the first duty.” He continued, “[T]he preservation of our lives … is the end of war, and the possession or acquirement of things necessary and useful to life is most suitable to those principles of nature, and to use force, if necessary, for those occasions, is no way dissonant to the principles of nature… .”

More than a century and a half later, the Framers of the U.S. Constitution—keen students of Locke and Grotius, as they were—would capture this in positive law. Article VI of the Constitution requires that “all Treaties made” be “in Pursuance” of the Constitution. This understanding survived even after the United States ratified the 1949 Geneva Conventions, with the U.S. Supreme Court holding in Reid v. Covert (1957), “This Court has regularly and uniformly recognized the supremacy of the Constitution over a treaty.”

To be clear, the argument here is not that a sovereign’s just resort to force under its duty to defend its people overrides any requirement of restraint or moderation in the use of force. Rather, the argument is that any requirement for moderation cannot supplant a legitimate, just need for self-preservation. Similarly, the argument is not that a belligerent acting in self-preservation may disregard or violate jus in bello to achieve its ends. Instead, it is that any purported legal obligation that demands a just State sacrifice itself is a legal farce—i.e., not law—no more binding than, as Cicero put it, “the rules a band of robbers might pass in their assembly” to apportion stolen property.

These precepts are anything but quaint relics of history. Even today, the right of self-preservation remains the foundation of political society, the modern nation-state, and the ordering of sovereign duty. Although commentary claims the law has “transcended” or “evolved” beyond it, no contemporary account of LOAC has persuasively explained how one might unwind this foundational hierarchy of law without collapsing the very sovereign authority international law presupposes.

Modern Acceptance of Suicidal Restraint

None of this, however, has stopped many modern LOAC scholars from embracing suicidal restraint; i.e., compliance that materially increases the probability of a State’s destruction, territorial dismemberment, or the functional annihilation of the political community.

We’ll start with Common Article 1, which obligates parties to the 1949 Geneva Conventions to “respect and to ensure respect for the present Convention in all circumstances.” Both the 1958 and 2025 versions of the International Committee of the Red Cross (ICRC)’s Commentary to the Fourth Geneva Convention urge a literal interpretation of the article, with the latter insisting readers be mindful of the “strict separation of jus ad bellum and jus in bello as one of the basic safeguards for compliance with the Conventions.” It rules out military necessity as a basis for breach, saying, “It is generally agreed that military necessity, subject to provisions that specifically provide for exceptions, may not justify violations of the Conventions as military necessity has already been taken into account in the formulation of their provisions.”

There is also Article 60(5) of the Vienna Convention on the Law of Treaties, which excludes “provisions relating to the protection of the human person contained in treaties of a humanitarian character” from treaties that may be terminated or suspended as a consequence of breach. “Thus, in case of a breach of such a treaty, the innocent States are not entitled to invoke the breach as a ground for suspending or terminating [humanitarian law treaties] … as this would invariably deprive the individuals of their protection under the treaty” (Villiger, Commentary on the 1969 Vienna Convention on the Law of Treaties, p. 747).

And the Hostages case? The Nuremberg Military Tribunal (NMT) wrote, “As we have previously stated in this opinion, the rules of international law must be followed even if it results in the loss of a battle or even a war. Expediency or necessity cannot warrant their violation.” The tribunal concluded the Nazis should have “limit[ed] [their] operations or withdraw from the country in whole or in part… .”

Dispositive as they may seem, these provisions of law—or more precisely, interpretations thereof—are nothing more than a simulacrum of law. LOAC exists to regulate the conduct of States that, at a minimum, must survive in order to bear any legal obligation in the first place. Indeed, not only should LOAC accommodate self-preservation, it must do so for its own survival; a “dead” State cannot “respect” or “ensure respect” for anything.

But does that mean that each of these positive provisions is facially unlawful? Of course not; these provisions only survive—and are most useful to humanity—if they impose obligations of suicidal restraint asymmetrically; that is, on the aggressor, not the defending State.

Reciprocity as LOAC’s Guarantor

From its earliest days, LOAC relied on reciprocity as its central load-bearing feature. Reciprocity embodied sovereignty’s primacy, the subordinate role treaty obligations assume vis-à-vis military necessity, and equality as a principle of law. The Lieber Code unequivocally forbade “all cruelty and bad faith concerning engagements concluded with the enemy,” “wanton violence,” and the “rape, wounding, maiming, or killing” of civilians, but conceded “[t]he law of war can no more wholly dispense with retaliation than can the law of nations, of which it is a branch. … A reckless enemy often leaves to his opponent no other means of securing himself against the repetition of barbarous outrage.” In practice, such “retaliation” could lawfully include reciprocal “no quarter” orders and death for any enemy of the United States who enslaved or sold captured Union soldiers.

Importantly, the relevance of reciprocity here is not that it authorizes uninhibited cruelty, but that it reflects the long-standing recognition that restraint binds as law only where it does not operate as a unilateral demand for self-destruction.

A few years after the Lieber Code, Article 14 of the 1868 Additional Articles to the 1864 Geneva Conventions, provided that, in naval warfare, if there exists “any strong presumption that either belligerent takes advantage of the benefits of neutrality, with any other view than the interest of the sick and wounded, gives to the other belligerent … the right of suspending the Convention as regards such belligerent.” What’s more, should this presumption “become a certainty, notice may be given to such belligerent that the Convention is suspended with regard to him during the whole continuance of the war.”

Of course, the 1868 Additional Articles were never ratified. But the natural justice of reciprocity endured. Two years later, the St. Petersburg Declaration included a carveout for when belligerents permitted to use banned munitions became a party to a conflict. Facing such a disadvantage, the Declaration expressly empowered party members to ignore the Declaration’s provisions. Article 2 of the 1899 Hague Convention contained a similar provision, saying it shall “cease to be binding from the time when, in a war between Contracting Powers, a non-Contracting Power joins one of the belligerents.” Reciprocity would likewise appear in Article 2 of the 1907 Hague Convention, which reads, “The provisions contained in the Regulations referred to in Article 1, as well as in the present Convention, do not apply except between Contracting powers, and then only if all the belligerents are parties to the Convention.” The 1907 Hague Convention, of course, earned broad ratification by every major military power.

Less than a century after the Lieber Code, Winston Churchill would similarly note the profound unfairness of demanding asymmetric compliance in international law, writing in The Gathering Storm (p. 492),

The final tribunal is our own conscience. We are fighting to re-establish the reign of law and to protect the liberties of small countries. Our defeat would mean an age of barbaric violence, and would be fatal not only to ourselves, but to the independent life of every small country in Europe. Acting in the name of the Covenant, and as virtual mandatories of the League and all it stands for, we have a right, and indeed are bound in duty, to abrogate for a space some of the conventions of the very laws we seek to consolidate and reaffirm. Small nations must not tie our hands when we are fighting for their rights and freedom. The letter of the law must not in supreme emergency obstruct those who are charged with its protection and enforcement. It would not be right or rational that the Aggressor Power should gain one set of advantages by tearing up all laws, and another set by sheltering behind the innate respect for law of its opponents. Humanity, rather than legality, must be our guide.

Even today, reciprocity remains the backbone of LOAC, even as positive law might sometimes indicate the opposite. “International humanitarian law (IHL) is often described as a triumph of principle over pragmatism; a set of rules meant to restrain war even when all else is breaking down,” wrote one scholar recently about reciprocity. “In practice, though, the logic of reciprocity continues to shape the ways States fight, negotiate, and justify restraint.” Indeed, reciprocity stands not just as a matter of fundamental fairness; it recognizes the adversary’s agency in choosing whether or not to follow LOAC. This is the key reason for the reciprocity paragraph in the 1949 Geneva Conventions’ Common Article 2: non-parties who complied with LOAC could trust that their enemy (a party to the Convention) would likewise be bound by LOAC. This created a powerful incentive toward humanitarian restraint for the non-party.

Self-Preservation and Asymmetric Legal Obligations

Turning back to the Hostages opinion, even this forceful, exhortative dictum betrays an underlying fidelity to first principles. At the outset, nothing in the opinion suggests the NMT intended to reverse longstanding precepts of self-preservation that had historically been accepted uncritically and universally. Even the court’s discussion of “The Irrelevance … of the Illegality of Aggressive War” amounts to nothing more than a rejection of the idea that States fighting a just war may categorically disregard the laws of war. That rejection is very different than saying the universality of jus in bello must be blind to the concrete facts, stakes, and threats facing each belligerent.

Moreover, even where the court recognized a separation between jus ad bellum and jus in bello, it was the Nazis who had a duty to suffer military defeat—or “limit [their] operations or withdraw from the country in whole or in part”—in subservience to positive law. If the “why” of war truly had no bearing on the “how,” then the law could just as easily recognize a duty on the part of the resistance fighters in Hostages to submit themselves politically to the occupying force, even to the point of incurring death. Yet the tribunal allocated responsibility and the duty to embrace defeat upon the aggressor, not upon those fighting to expel foreign aggression. Even today, no “duty to surrender” exists in international law (at least for defending States, as the Hostages court implies), even though direct participation in hostilities may lawfully subject a civilian to attack and prosecution under the law of the occupying power (not the displaced sovereign’s law).

Lassa Oppenheim, whom the NMT cites favorably in its discussion of the separation between jus ad bellum and jus in bello, speaks precisely to this point. “[I]t becomes more and more recognised that violations of other States in the interest of self-preservation are excused in the cases of necessity only,” wrote Oppenheim (International Law, vol. I, p. 178) (emphasis original). He continued, “Such acts of violence in the interest of self-preservation are exclusively excused as are necessary in self-defence, because otherwise the acting State would have to suffer or have to continue to suffer a violation against itself.” And how might we know whether a State may lawfully avail itself of necessity’s excuse? Even as a “hard and fast rule” eluded Oppenheim, he concluded that “every State must judge for itself when a case of necessity has arisen… . Everything depends on the circumstances and conditions of the special case…” (p. 179). I will go one step further: States make this call because States—not LOAC—bear protective responsibility for their people, not as an extra-legal exception à la Carl Schmitt’s decisionism, but as a limit internal to the classical ultra vires tradition.

With this interpretive backdrop, we can better understand the extent to which jus ad bellum and jus in bello are separate, yet fundamentally linked branches of international law. On the one hand, we were never supposed to deny aggression’s relevance to jus in bello questions, only understand that a just cause does not excuse wholesale suspension of LOAC’s protections. On the other hand, where an aggressor initiates war in pursuit of domination, conquest, or destruction, it ruptures the moral and juridical basis for insisting on symmetrical restraint. As a result, the State that resorts to force for reasons of elective ambition will carry a greater legal burden than one that resorts to force out of existential necessity. That does not mean the defending State receives a license to commit atrocities, but rather, it is no longer bound to observe any purported obligation whose fulfillment would threaten its continued political existence.

Concluding Thoughts

Some have argued that “[m]ilitary necessity generally runs counter to humanitarian exigencies” and, accordingly, call upon States to “strike a balance between military necessity and humanitarian exigencies.” This framing, which imagines two coequal interests in tension with each other, is intuitively appealing, but ultimately false. In just wars, military necessity does not stand opposite humanitarian law as a counterweight. It defines the outer boundary within which humanitarian obligations can lawfully and meaningfully operate.

That boundary is necessarily exceptional. It applies rule-by-rule rather than categorically and does not license indifference, cruelty, or expediency masquerading as necessity. Whether a State invoking necessity has crossed the line is a question for the trier of fact, the risk of which the State assumes. Yet where a State, having submitted the facts of its case to a candid world, proves its good-faith plea of necessity, the law accommodates.

Indeed, humanity directing positive law—not the inverse—is the proper ordering of things. As a matter of law, no provision of LOAC may be construed to require a State acting in lawful self-defense to accept its own destruction as the price of compliance. Furthermore, any law that places the burden of suicidal restraint on the victim of aggression rather than on the aggressor who precipitated the existential crisis is not really “law,” but an unjust claim beyond law’s competence to command obedience. In such instances, States not only have the option, but for humanity’s sake, the duty, reject such interpretations as binding law (lex injusta non est lex). And as this post argues, this is just as much for LOAC’s sake as it is for the defending State’s sake.

When States fail in this duty of disobedience, they contribute to the creation of a fake law of war that empowers bad-faith actors, for which humanity—the very thing humanitarian law should protect—pays the price.

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Thomas Wheatley is a major in the U.S. Army and an editor for Articles of War. He is also an Assistant Professor in the Department of Law at the United States Military Academy, where he teaches U.S. constitutional and military law.

The views expressed are those of the author, and do not necessarily reflect the views or official position of the United States Military Academy, Department of the Army, Department of Defense or its components.

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Photo credit: U.S. Air Force, Staff Sgt. N.W. Huertas