Crimes against Humanity and International Legality in Legal Theory after Nuremberg

Sévane Garibian. Journal of Genocide Research. Volume 9, Issue 1. March 2007.


The question most often raised about the trial of the major war criminals before the International Military Tribunal (IMT) at Nuremberg seems, at first sight, to turn on the nature of the judgment. Traditional doctrine distinguishes legal from political disputes, maintaining that international law applies only to the former. In the present paper, however, we shall be following the reasoning of the legal theorist Hans Kelsen, who has sharply criticized this “hypocritical,” “dangerous” view. According to Kelsen, legal disputes are disputes settled through the application of legal norms found in pre-existing positive law. Political disputes, on the other hand, are settled through the application of general principles of equity and justice, that is, new norms created by an (international) judge with a view to resolving a particular conflict.

In Kelsen’s estimation, every dispute is “justiciable” and is therefore a legal dispute. Furthermore, international law is always applicable and is applicable in all cases: either the international law in force prohibits and sanctions one or another of the ways of behaving at issue in a dispute, in which case an appropriate condemnation can be pronounced; or it says nothing about the behaviour at issue, in which case no condemnation can be pronounced, on the principle that “whatever is not forbidden is permitted.” It sometimes happens, however, that the application of existing international law, albeit possible from a logical standpoint, is politically or morally unsatisfactory. Resolution of conflict through jurisdictional creation of new general norms is a case in point.

This critique leads us to displace the question. It suggests that the legal or political character of a dispute depends not on its nature—and thus on the nature of the judgment—but on the nature of the norms used to resolve the conflict. Thus the theoretical question posed by the Nuremberg judgment is not “what is the nature of this judgment?” but “what is the nature of the norms brought to bear by the International Military Tribunal?”

The interest of the question as to the nature of the norms contained in the Charter of the IMT resides in the fact that it ultimately requires us to consider both the fundamental problem facing the actors at Nuremberg, and also the main objection raised by the IMT’s adversaries, particularly the defence lawyers: the incompatibility of the law of Nuremberg, especially Article 6 (c), which defines “crimes against humanity” for the first time, with the principle of the legality of the delicts and sanctions and its corollary, the principle of non-retroactivity.

According to these principles, every punishable act and every sanction must be foreseen by a written text prior to the commission of the acts involved. But the defence at Nuremberg pointed out that the concept of “crimes against humanity” and the principle of individual responsibility for international crimes did not exist in the international legal order at the time the acts were committed. Consequently, judging agents of a state for a crime against humanity amounted to breaching the principle of legality. This is the main argument (derived from the classic positivist theory on which the discourse of the IMT’s detractors was premised) that the doctrine developed in the years 1945–1950 sought to refute.

A close reading and a reexamination of the European and Anglo-American literature produced immediately after the Nuremberg judgment, on the occasion of the IMT’s 60th anniversary, is particularly interesting in regard of its influence in international criminal law concerning the significance of legality. This literature reveals that two different strategies were used to refute claims to the effect that the Charter of the Tribunal is incompatible with the principle of legality. Either the scholars grant, echoing the judges’ reasoning, the fiction according to which the Charter is merely the expression of pre-existing norms of international law, making the law of Nuremberg compatible with the principle of legality, in which case they ignore the question of the new charge of crimes against humanity; or they admit that the Charter, especially Article 6 (c), about crimes against humanity, creates new, retroactive law, thus conceding that the law of Nuremberg is incompatible a priori (or is only partially compatible) with the principle of legality. In the second case, they go on to justify the breach of the principle of legality.

Whichever strategy is adopted—denial or justification—the doctrine examined here sets out to show that the problem of the compatibility of the law of Nuremberg with legalistic requirements is a false problem. In both cases, we are confronted with the difficult problem of the standard of legality in the international legal order, a question to which neither the authors of the London Agreement nor the international judges at Nuremberg can be said to have responded. Any such response would presuppose taking a position on the nature and specificity of international law, and the limits on the principle of legality in this juridical order. Once this is grasped, it will readily be seen that the real problem thrown up by the punishment of crimes against humanity stems from the Nuremberg actors’ reluctance to interfere in Germany’s internal affairs out of respect for the principle of state sovereignty.

For obvious reasons, the present study ignores scholars for whom the question of the requirements of legality in international law is irrelevant. Three kinds of scholars are involved. There are, first, those who, even if they acknowledge, as some do, that the law of Nuremberg can be criticized from a strictly legalistic point of view, nevertheless regard the Charter of the IMT as the incarnation of a superior natural law, in the Grotian tradition. Others, in the classical positivist tradition, consider the law of Nuremberg to be not law, but political action. Finally, a third group of scholars sets out from the premise that the principle of legality, a principle of national law, does not apply in the international legal order (contrary to what was at least implicity admitted by all the actors at Nuremberg: those who drafted the Charter as well as the accusation, the defence, and the court).

The Nature and Specificity of International Law

Whether those who have written about the Nuremberg Charter regard this text as an expression of pre-existing international law or a creation of new, retroactive law, they all agree that international law is in its early stages and has a decentralized structure, from which its customary nature derives. Differences of opinion emerge, however, when it comes to drawing conclusions about the nature of the norms contained in the Charter of the IMT. Whether or not commentators take a position as to the limits of the principle of legality in the previously established international legal order is decisive here.

International Law: A Primitive, Decentralized Legal Order

In the opinion of all the authorities examined here, international law constitutes a legal order that may be called primitive in the sense that it tends to evolve a posteriori: the norms of international law arise in response to needs, rather than anticipating them. International law is said to be “at the stage at which national legal orders found themselves at the beginning of their development.” Comparisons with the slow evolution of national legal orders are often drawn to illustrate the technical imperfection and “dynamic” (that is, evolving) nature of the international legal order, which is said to be in a phase of rapid expansion.

Again, one of the particular characteristics of international law, precisely because it is primitive, is that it is decentralized: “in contrast to technically well developed legal orders, it does not possess central organs specializing in making and executing law.” In 1945, the international legal order was not endowed with any permanent legislative and judiciary organs, even if the creation of the League of Nations and, subsequently, the United Nations represented undeniable advances in the centralization process. It was the decentralized nature of international law which brought Kelsen to the conclusion, as early as 1934, that it was an illusion to think (following traditional voluntarist doctrine) that international law might be based solely on the good will of states and the public opinion of the world’s peoples. This could only lead, according to Kelsen, to “inter-state anarchy” in the true sense of the word: as national legal orders are based on the will of sovereign states, so international law should be based on the will of an international community.

State sovereignty should accordingly be understood in a relative sense, as “sovereign equality.” In question is a basic principle of public international law; it stipulates the independence, not the omnipotence, of states, codified in Article 2 of the United Nations Charter and recognized as such by the Nuremberg judges as well as by the doctrine that sprang up around the IMT. According to this principle, every state is sovereign to the extent that it is subjected, directly and immediately, to international law alone, not to the domestic law of any other state. With regard to the particular question of Germany’s status at the end of World War II, majority opinion has it that Germany ceased to exist as a sovereign state with the Berlin Declaration of June 5, 1945. Since the unconditional surrender had effectively confirmed the disappearance of the German state, sovereignty was vested in the four powers that were the Reich’s successors, and the London Agreement was binding on Germany as well, even if Germany was not one of the signatories.

Finally, as in the process (taken as a model) by which national legal orders evolve, the technical development of international law, it is argued, should begin with the judiciary process, even before a central legislative body is established or international law is codified, as it must eventually be: “this state of complete decentralization … is followed by the emergence of the first central organs, which are not law-making organs, as might be supposed, but organs of jurisdiction.” International law is the imperfect result of “the instincts of justice and humanity that are the common heritage of all civilised nations.”

International Law: A Legal Order of a Customary Nature

Both primitive and decentralized, international law is, first and foremost, customary law. Anglo-American scholars often draw parallels with common law in order to illustrate the importance, in the international legal order, of “what is indicated by reason,” as opposed to “what is commanded by sovereign authority.”

More concretely, it may be observed that Article 38 of the Charter of the International Court of Justice (ICJ) is cited by a large majority of writers when what is in question is the formal sources of international public law. These sources are: particular or general international conventions (38 (a)); international custom, as evidence of a general practice accepted as law (b); the general principles of law recognized by civilized nations (c); and, lastly, judicial decisions and opinions, considered as subsidiary means for determining the rules of law (d).

Consequently, some scholars (Anglo-Americans, as a rule), endorsing the judges’ reasoning, hold that the Nuremberg Charter is an expression of pre-existing norms of international law. The law of Nuremberg is thus held to be in conformity with the requirements of legality. To rebut legalistic critiques, these writers present the Charter of the IMT as the codification of a customary international law whose ultimate basis is the “conscience of the international community,” which alone makes it possible to determine what is permitted and what is forbidden. Thus the Nuremberg Charter is deemed to have assembled pre-existing norms that had previously been scattered; they are said to justify considering the acts of the Nazis as constituting criminal behaviour at the time of their commission.

Those who defend this opinion specify the pre-existing norms involved. They are, in the first instance, treaties (especially the Hague Conventions of 1899 and 1907, the Treaty of Versailles and the League of Nations Covenant of 1919, the Pact of Paris of 1928 and the Declaration of Moscow of 1943), but also, more vaguely, the customs and general principles of justice, although these customs and principles are never defined or spelled out. It is noteworthy that the Allies’ political declarations about, and condemnations of, Nazi crimes from 1941 on are cited as illustrations of the practice of states that goes to make up international custom, or as an expression of general principles accepted by all civilized nations. According to these writers, the points evoked all make it possible to affirm that the Nazis were aware of the criminal nature of their acts at the moment of commission—the more so, some add, as the acts incriminated in the Charter of the Nuremberg Tribunal already constituted crimes as defined by the criminal codes of the four powers and all civilized states.

Thus, in the view of some writers, the judgment of Nuremberg is not based on new, retroactive law; the Charter of the IMT constitutes “the repository of the crystallized conscience of mankind.” A very few mention, furtively, the specific criticisms directed against Article 6 (c) of the Charter, only to reject them without lengthy discussion; all the others refrain from taking a position on the legality of the new charge of crimes against humanity, absent from most commentaries on the Charter. In the opinion of these scholars, moreover, silence is the rule when it comes to the question of the significance of, and limits on, the principle of legality in international law. When this principle is mentioned at all, it is in order to affirm that it should not be accorded too much importance in the international legal order, or, again, that it is in any case not binding where war crimes are concerned.

Generally speaking, the conclusive idea expressed in this part of the doctrine is that the law of Nuremberg, even if it is imperfect or sometimes imprecise, is not new, retroactive law, and is sufficiently complete to serve as a model for the future. One question, however, remains unanswered: just how precise does the principle of legality require the norms of international criminal law to be?

The Limits of the Principle of Legality in International Criminal Law

In international criminal law, the question as to what legality means is both particularly interesting and particularly thorny. It had never been raised before Nuremberg. The situation in 1945 was a very special one: whereas the provisions of international law had been applied, as a rule, by national jurisdictions operating in conformity with principles defined by national legal orders, involved here were international norms that were to be applied directly. The authors of the Nuremberg Charter opted for the monist approach, which, giving precedence to international law, recognized the direct application of the law of Nuremberg, the criminal responsibility of individuals as subjects of international law, and international law’s independence of national laws. In this case, therefore, the question of legality has to be apprehended in the framework of an international criminal law applied directly to the accused. But, at the time, there existed not a single international text treating this principle.

What is more, the multidisciplinary (combining comparative criminal law and public international law) and customary nature of international criminal law considerably complicated the task of determining the standard of legality. Finally, although the principle of legality has, since the Enlightenment, been a fundamental principle of most national legal orders, its meaning varies with the legal theory a given legal order presupposes. It was nevertheless observed, in 1945, that the criminal law of most states, whether Anglo-American or European, was structured around three major common axes: the prohibition (relative or absolute) of retroactive criminal law; and the principles of the legality of, first, delicts and, second, punishments, with resort to reasoning by analogy tolerated within certain limits.

Neither the actors at Nuremberg (including those who drew up the Charter of the IMT) nor the authors of the doctrine which contends that the Charter was the expression of pre-existing norms of international law take a clear-cut position on the meaning and requirements of international legality. One can, however, find certain indications as to how this question might be broached in the writings of the more critical commentators who begin by affirming that the Charter contains new, retroactive law in order then to justify this state of affairs by appealing to the “elasticity” and/or the limits of the principle of legality.

Because of the inclusion, in the absence of any real debate on principles, of the concept of crimes against humanity in the Nuremberg Charter, it would appear that the Charter’s defenders have looked for ways to increase its credibility or legal value by a process of a posteriori justification. They have tried, as it were, to determine the “minimum quantity” of positive law sufficient to produce a valid norm in international criminal law.

“Elastic” Legality in International Law

Whereas legalistic criticisms of the law of Nuremberg set out from the premise that legality always means the same thing in national legal orders and the international legal order, the scholars examined in the present paper usually begin by taking a more finely shaded position on this question.

Of course, the principle of the legality of delicts and sanctions, with its corollary, the principle of the non-retroactivity of criminal law, is, according to most commentators, recognized by the national law of all civilized nations. Cited by way of example are, notably, Articles 5 to 8 of the 1789 Declaration of the Rights of Man and of the Citizen, Article 4 of the French Criminal Code of 1810, Section 2 of the German Criminal Code of 1871, Article 116 of the Constitution of the Weimar Republic, and, in very general fashion, the prohibition on retroactive rules in Anglo-American law (“ex post facto rules,” or, in the sense given the term in the US Constitution, “retroactive law”).

Yet the foregoing does not imply that, on the one hand, this principle is absolute, or, on the other, that it is interpreted in exactly the same way in Roman and Anglo-American law. Nor does it imply that it can be applied “as is” in the international legal order. In addressing the first two points, Kelsen, for example, begins by recalling that the principle of legality admits several exceptions: it applies only in the field of criminal law, and does not apply when the retroactive criminal law is advantageous to the accused. Kelsen goes on to note that in certain systems, such as the system of common law, this principle has never been construed as constituting a limit on sovereign legislative power. Finally, he adds that the principle of non-retroactivity, in particular, is valid only for legislation, to the exclusion of customary and/or judicial creation of law, which is retroactive by definition.

As far as the third point is concerned—the application of the principle of legality in the international legal order—Kelsen’s position is categorical: no general norm of international law prevailing at the time guaranteed the principle of legality or prohibited concluding treaties that establish retroactive norms. To maintain, for instance, that retroactivity is prohibited in the international legal order is to presuppose two conditions which, according to Kelsen, are probably not fulfilled: first, that “the general principles of law recognized by civilized nations” (Article 38 (1) (c) of the Charter of the ICJ) constitute positive international law, and second, that the principle of non-retroactivity is one of these general principles. To treat these principles as coming under positive international law amounts, Kelsen argues, to abandoning positivist doctrine.

We find less cut-and-dry discussions of this point in most other writers, who obviously prefer to centre their justification of the relativity of the principle of legality in international law on the customary, evolving nature of this principle. It must, they argue, be applied in flexible, “elastic” fashion in international criminal law, in conformity with the non-codified, dynamic character of the international legal order. Henri Donnedieu de Vabres observes further that, according to the Nuremberg judges, the principle nullum crimen sine lege does not limit state sovereignty: it merely formulates a widely observed rule.

A Legality Restricted by the Superior Principle of Morality

Regardless of its relative character in international law, the doctrine we are examining here affirms that the principle of legality should, as a general rule, be interpreted as restrictively as possible. Furthermore, whether or not it is acknowledged in the international legal order, it does not apply, the contention is, to the London Agreement. The arguments used to justify this conclusion rest on the premise that the principle of legality is, above all, a principle of justice flowing from natural law doctrine; this premise is invoked against that adopted by the IMT’s detractors in the name of classical positivism.

The interest of this premise resides in the fact that it grounds a line of reasoning, worked out with greatest precision by Kelsen, which manages to elude the Law vs. Morality dilemma that confronted, notably, the IMT’s judges, while simultaneously eschewing any form of compromise, theoretical or juridical. It resolves the question of the legality of the law of Nuremberg by positioning itself on the terrain of a conflict between two principles of justice.

When two principles of justice conflict, the higher of the two prevails. For example, the well known principle of justice (which admits of no exception) according to which “ignorance of the law is no excuse” prevails, Kelsen argues, over the principle of justice according to which “the law must be known in order to be applicable.” At Nuremberg, he goes on, the Tribunal rightly condemned the accused Nazi leaders for acts that were manifestly immoral, even if these acts were not subject to punishment under positive international law at the time of their commission. The principle of legality is not applicable here, because the retroactivity of the new norms created by the London Agreement is fully justified by a higher principle of justice widely acknowledged by the civilized world: condemning individuals “morally responsible” for the international crimes of World War II, says Kelsen, certainly has to be considered much more important than strictly respecting the altogether relative principle of non-retroactivity.

We must, Kelsen points out, distinguish a retroactive norm that makes punishable an act which was “indifferent” or “innocent” when it was committed (in this case, the retroactivity of the norm would be unjustified) from one that makes punishable an act considered “immoral” or “in conflict with a higher norm” at the moment of its commission. The acts committed by the accused Nazi leaders certainly fall into the second category. Hence retroactivity is here justified, in Kelsen’s view, because the behaviour that the Nuremberg Charter subjected to punishment undeniably constituted a violation of the higher principles of morality. The Charter of 1945 simply transformed a patent moral responsibility into a legal one.

Scholars such as Goodhart, Donnedieu de Vabres, Genton, Ehard and Merle come to the same conclusion, although they are less precise. All concede that the principle of legality can, in this case, be restricted by higher general principles such as justice or equity. The idea on which they agree is the affirmation that, in certain limit cases, a solution resulting from the positive law in force at the time of commission may be morally unsatisfactory, so that, in such cases, one is entitled to choose “the lesser of two evils”: in other words, accept the creation of retroactive norms rather than allow immoral, abhorrent acts to go unpunished. This idea, be it noted in passing, became the subject of a 1958 debate on the condemnation of Germans who “informed” under the Nazi regime.

Generally speaking, the determining factor in such circumstances is not, on this line of reasoning, the subject’s concrete knowledge of the law at a given time, but, rather, whether it was possible for him to know the abhorrent nature of his conduct. Moreover, as far as the standard of legality applicable to delicts and sanctions in international law is concerned, it would appear that, given the nature and specificity of this legal order, a strict definition of the infraction and/or a precise formulation of the sanction risked by the agent of the infraction are by no means required.

Thus the doctrinal analysis that seeks to show that the problem of the legality of the Nuremberg Charter is a false problem also enables us to bring out the most important constraint put on the Tribunal: respect for the “sacrosanct” principle of state sovereignty, which implies non-interference in the internal affairs of other states. While such interference was deemed acceptable in the case of war crimes, it was still, in 1945, a source of embarrassment and uneasiness when the issue was interference for the purpose of repressing crimes committed in peacetime, such as the crimes against humanity perpetrated by the Nazis before 1939. Nuremberg left the question of crimes against humanity in the strict sense “unresolved”; the Tribunal consistently linked such crimes to war crimes. In Elizabeth Zoller’s estimation, there is a simple explanation for this: the concept of a crime against humanity and the juridical regime that follows from it “virtually abolish the international legal order and the sovereignty that founds it.”

Coming immediately after the Second World War, the law of Nuremberg was ultimately only one stage in a process. Although it was imperfect, ad hoc law, it nevertheless had the advantage, in the opinion of some people, of lending truly concrete form to the emergence of “international society as a legal community.” It also had the merit of exposing the major shortcomings of nascent international criminal law and of making it possible to draw conclusions for the future.


The doctrine examined here suggests that it is, to begin with, necessary to “generalize” the law of Nuremberg in order to make “the law of a moment” a “moment of the law.” A first step in this direction was taken with the adoption by the United Nations General Assembly on February 13 and December 11, 1946 of, respectively, Resolutions 3 (I) and 95 (I), which contributed to the recognition of the law of Nuremberg as customary law. The intent nevertheless was, as the text of Resolution 95 (I) makes clear, “the gradual development and codification of international law” in the form of a general codification of offences against the peace and security of mankind.

Second, with regard to crimes against humanity in particular—”the key to universal criminal law”—the doctrine in question suggests that the definition of them should be expanded, and the punishment of these crimes based on the protection of human rights, in order to ensure that the question of human rights can be treated beyond the context of armed conflict. Although Article 1 of the United Nations Charter of June 16, 1945 declares this to be one of the purposes of the United Nations, the Charter also guarantees the preeminence of the sovereignty and independence of states (Article 2). Thus the precondition for the proper definition and effective repression of crimes against humanity is the promulgation of an international Declaration of Human Rights requiring all states to guarantee their citizens or subjects certain basic civil and political rights, and, further, assigning political and juridical organs of the international community the task of seeing to it that these obligations are met. Any crime against humanity would then constitute a violation of human rights, in times of peace as well as in times of war; an approach that has lately found its expression in the case law of the International Criminal Tribunals (ICT) for the Former Yugoslavia and for Rwanda.

Finally, the post-Nuremberg doctrine emphasizes that a permanent international criminal jurisdiction must eventually be created, making it possible to judge clearly defined international infractions constituting a breach of the international public order. As far back as the 1930s, Kelsen pointed out that this was a technical sine qua non for genuine progress in international public law and a first step toward the centralization of this legal order. Many different texts on doctrine written in the wake of the Nuremberg experience are based on the same idea, which was also the focus of the debates leading up to the December 9, 1948 Convention on the Prevention and Punishment of the Crime of Genocide and, more recently, the July 17, 1998 Statute of the International Criminal Court (ICC).

The general conclusion to be drawn after Nuremberg might be summed up as follows. The international criminal law and the effective punishment of crimes against humanity presuppose “a struggle to create and consolidate a democratic international sovereignty, that is, an international public order that will put an end to criminal sovereignties and protect the Rights of all Human Beings.” The shortcomings of the law of Nuremberg confirm that the punishment of crimes against humanity—which have been since then recognized and legally defined as international crimes—is indissolubly bound up with the preservation of peace and the protection of human rights. The law of the ICT for the Former Yugoslavia and for Rwanda, like the Statute of the 1998 ICC, fully reveals this essential bond, while finally disconnecting the concept of crime against humanity from war. Also, if the Nuremberg precedent raised for the first time the question as to what legality means in international criminal law, the examined literature indicates both the importance and “elasticity” of international legality regarding the nature and specificity of this legal order. This concern with the international requirement of the principle of legality has been recently confirmed and specified, as evidenced in the UN Secretary General recommendations, the ICT’s case law, and the Statute of the ICC—which expressly guaranties, for the first time in international criminal law, strict respect for this “general principle of international law.”