Of Open and Closed Systems – War Caught in Lotus and Anti-Lotus
Within every system of law there are open legal sub-systems that offer residual freedom to act and closed sub-systems where residual prohibitions prevail. In the first, the maxim is that what is not prohibited is permitted. In the second, that which is not allowed or affirmatively authorized is prohibited.
The first of these is a Lotus-system; the second is an anti-Lotus one. Reference here is to the famous case The S.S. Lotus at the Permanent Court of International Justice—predecessor to the International Court of Justice—where the Court explained that in general international law, the prevailing rule is that an absence of prohibition (or more broadly regulation) denotes freedom to act (p. 18-19). In the general system of international law, some degree of Lotus-freedom is unavoidable. Because international relations are composed of endless actions and omissions, it would be unimaginable to require a specific or even implied permissive rule in every case. Moreover, such an approach would be at odds with the sovereignty of States, which implies a certain degree of freedom to act, a freedom cherished in practice.
This does not, however, mean that the Lotus freedom operates at every step of legal reasoning. That is, freedom of action does not always result simply because there is no conventional rule applicable. In such cases, legal advisors must also consider the availability of a customary rule, a general principle, or an available legal analogy. Lawyers may also consider freedom of action, or lack thereof, at different levels according to absences of: express provisions of the legal order; implicit injunctions; injunctions obtained by analogy, whether limited or extensive; injunctions obtained through the application of general principles of law or by considering the intrinsic rationales of the legal system; or injunctions obtained by taking into account the general values of the legal system or the social necessities of the moment. The scope of our Lotus rule of freedom decreases progressively in these situations respectively (for more on this point see Kolb, p. 100 et seq.).
Additionally, legal sub-systems—the regimes that operate in support of the general system of public international law—can either be open or closed. The level at which a lawyer should shift towards freedom of action or away from it must therefore carefully be determined and can vary considerably in the context of some legal sub-systems. In the context of war, we find both systems, open and closed, pitching the jus ad bellum against the jus in bello with differing rules concerning freedom of action to some extent.
Jus ad Bellum
The jus ad bellum sub-system is presently a closed one, albeit manifestly under heavy challenge and routine defiance. The general rule of the current system is a prohibition on the use force (UN Charter, art. 2(4)). That prohibition is subject to a series of exceptions, the generally accepted ones being: self-defense; authorization by the UN Security Council under Chapter VII of the UN Charter; and invitation by a government for armed action on its territory. This legal complexion means that if a State or actor cannot base itself on an entitlement to use force under the list of accepted exceptions, its use of force is legally unlawful. In other words, the use of force is prohibited when a use of force is not authorized or allowed (anti-Lotus). The fact that some of the exceptions can give rise to broad interpretations (e.g. self-defense) does not detract from this legal situation.
Historically, however, this position of the jus ad bellum has fluctuated. The time of Grotius, and his famous De Jure Belli ac Pacis (1625), witnessed another type of closed system. Grotius recognized three forms of just war: defense; recuperation; and punishment (vol. II, I, 2, 2). According to Grotius, if there was no such basis to a war, it was unjust and could not be waged lawfully. Though archaic by now, this system is based on the same residual trigger as the modern system of the UN era, even if the general coloring is that of just war doctrine and not the bellum legale-idea of the modern law. It must be keenly noted, however, that just war doctrine was also a legal doctrine at the time Grotius wrote. Natural law, under which this doctrine was crafted, was not just a matter of morals and policy; it was also a matter of law.
However, by the 19th century, according to the most common reading of the law then applicable, there was no general prohibition to wage war or to use force through so-called forcible measures short of war. A State was thus entitled to use force as part and parcel of its sovereign power. If that is true, sovereignty provided a sort of general power to use force. This can be seen either as a blanket authorization or as a residual authorization, absent prohibitive rules. The system was, under this guise, an open one.
Jus in Bello
The traditional law on the conduct of hostilities, i.e. what is often called Hague Law, is based on the idea of a series of prohibitions as to weapons or methods of war, with a residual freedom to use the means and methods not prohibited. The prohibitions all stem from the cardinal idea of a prohibition of indiscriminate destructiveness (principle of distinction) or excessive suffering (principle on unnecessary suffering). Beyond that pale, war and belligerents have their way and sway. The system is therefore an open one, based on a Lotus logic.
However, the threshold at which the jump into permissiveness occurs has been importantly limited in the modern law. The Martens Clause, indeed, prohibits use of certain means or methods of warfare even though the law does not specifically or impliedly prohibit them. Belligerents must ensure the use of such means or method is compatible, amongst others, with the principle of humanity or of humane treatment.
Contrary to what is sometimes said, this legal situation does not mean that the system has become closed; Martens has not killed Lotus. The point instead is that when the conclusion that some course of action is lawful has been made—because it is not prohibited—the test of “humanity” must also be passed. That is, an act is lawful when a commander and legal advisor find that conduct does not offend the basic requirements of humanity (admittedly, an open-ended standard). Thus, if conduct is considered not to offend the Martens Clause, it remains permitted because no prohibition stands in its way, a diminished, but still an active form of the Lotus rule.
In the law on the protection of persons, i.e. so-called Geneva Law, the residual freedom principle, rooted in Lotus, has a less firm standing. This is so not because the laws of humanity have a more solid ground than in the law relating to the conduct of hostilities. Instead, the basic idea is that certain conduct not expressly or impliedly prohibited and not at odds with the principle of humanity can be applied here as it is in Hague Law.
The crucial point is that Geneva Law contains many more “positive” rules (obligations to act) rather than mere “negative” rules (obligations not to act). When a rule says “a State shall do X,” it opens no space for a residual freedom; there is no “backroom” of such a rule. To say that a State “shall do X” is not tantamount to saying it “may do Y.” On the contrary, if a rule says “A State shall not do Y,” behind that rule there is room for residual freedom to act; there is here a “backroom” of the rule because saying that A State is not permitted to do Y can mean it is allowed to do Z, the latter not being prohibited and not being otherwise affected by the Y rule.
Conclusion
The branches of international law relating to jus ad bellum and jus in bello show quite graphically how international law subsets of rules are either open or closed systems. Under the law as its stands today, the jus ad bellum is a closed system, wherein permission to act is based on the necessity of a permissive form. By contrast, large areas of the law on conduct of hostilities in the jus in bello are founded on an open system, where permission to act is not based on such a necessity. The former is thus considerably more constraining than the latter.
Far from being merely theoretical, there are important practical consequences to classification of a sub-system as either open or closed. This is especially true concerning interpretation and gap-filling. On interpretation, the closed system of jus ad bellum hinges on a rule and exceptions. The exceptions are, as a matter of sound legal principle, to be interpreted strictly (self-defense is indeed rarely so interpreted by interested States but is construed in a strict way by the ICJ). There is no such a priori consideration in an open system like the jus in bello rules for the conduct of hostilities. Its residual permission may be interpreted quite freely by comparison.
On gap-filling, the main point is that there are no gaps in systems that are either closed or open, by contrast with systems that are neither open nor closed. A “gap” in a closed system is automatically filled by prohibition. A gap in an open system is filled by permission. A system being closed or open seems thus to eliminate the ultimate possibility of gaps to be filled by additional legal reasoning. Contrariwise, in most parts of the law on protected persons (Geneva Law), the system is neither open nor closed, and thus gaps may occur and may be filled.
While requiring careful attention and explanation, this difference between the closed jus ad bellum and the open jus in bello (in its conduct of hostilities part) in fact, aligns with doctrinal and political orthodoxy. The modern law seeks to prevent war as a unilateral tool of State policy as far as possible but is based on the realistic consideration that once warfare has broken out, military necessities impose a certain freedom of action to overpower the enemy, and that a corset of too strict rules would have no chance to be ever implemented.
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Robert Kolb is a Professor of Public International Law at the University of Geneva and former legal staff member of the ICRC. Prof Kolb is also a member of the legal section of the Swiss military high command (IHL section).
The views expressed are those of the author, and do not necessarily reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.
Articles of War is a forum for professionals to share opinions and cultivate ideas. Articles of War does not screen articles to fit a particular editorial agenda, nor endorse or advocate material that is published. Authorship does not indicate affiliation with Articles of War, the Lieber Institute, or the United States Military Academy West Point.
Photo credit: U.S. Army, Sgt. Benjamin D. Castro
