The ILC must stay true to its progressive mandate and reject personal immunity for international crimes tried in national courts.

Two years ago, I published an article inLawfare decrying a late effort at the International Law Commission (ILC) to decriminalize aggression quietly through the backdoor. The article concerned the attempt by a latter-day cohort of the ILC membership to delist that particular transgression from the register of international crimes to which sovereign immunity must not apply in the criminal proceedings of the national courts of other states.
It is encouraging to see the ILC now on track to correct that avoidable mistake. Indeed, it has done even better: The revised draft text it adopted recently now not only relists the crime of aggression but also commendably lists two other related crimes—slavery and slave trade.
But while the ILC should be lauded for these developments, its stance on immunity remains problematic. The ILC draft text—relying on questionable conclusions drawn by the International Court of Justice (ICJ), whose mandate differs appreciably—has implied that only functional immunity is rejected by international law in the judicial proceedings of other states. The suggestion, then, is that the second kind of immunity, personal immunity, is recognized. This is not self-evident, and it leaves open a significant avenue for officials to evade accountability for their actions.
The Different Mandates of the ILC and the ICJ
The ILC is the expert body that facilitates the mandate of the UN General Assembly to “initiate studies and make recommendations for the purpose of … encouraging the progressive development of international law and its codification,” pursuant to Article 13(1)(a) of the UN Charter (emphasis added).
However, more often than not the ILC cohorts cast themselves in the image of the International Court of Justice, adopting the latter’s conservative approach to international law. In that mode, the ILC rarely interrogates the correctness of the ICJ’s analyses and pronouncements, including on the issue of immunity. Such a conservative approach may serve the ICJ in its own mandate; but it is unsuitable for the ILC.
The significance of these differentiated approaches will become clear later in this article. For now, it is only necessary to note that these differences arise from the respective remits of the ICJ and the ILC. Notably, Article 38(1) of the ICJ statute provides that “[t]he Court, whose function is to decide in accordance with international law such disputes as are submitted to it,” shall apply such principles of international as have been established already—most notably through treaties and customary international law (emphasis added). In contrast, Article 1 of the ILC’s statute necessarily makes it an agency of “progressive development”—and not the procuracy of conservatism, an approach that comes with the risk of stagnation or regression—of international law.
To that end, on the matter of deimmunizing state functionaries accused of international crimes and subjecting them to accountability in foreign national courts, the ILC may be needlessly limiting itself when it hews so closely to the pronouncements of the ICJ—the material aspects of which (as explained below) are of uncertain validity.
Two Kinds of Immunity Before National Courts
It is important to clarify from the outset that the work of the ILC on this topic exclusively concerns the question of whether or not immunity exists—or should exist—in the criminal proceedings of national courts of other states. It doesn’t concern the question of immunity before international courts and tribunals. There is no immunity of any kind in the proceedings of international courts and tribunals.
The ILC draft text indicates that it is only immunity of the “ratione materiae” classification (or “functional immunity”) that is not recognized in the judicial proceedings of other states. The problem with this is that it necessarily implies that the second kind of immunity—immunity ratione personae (or “personal immunity”)—is recognized.
Immunity ratione personae is the superior kind of immunity now reserved for three kinds of state functionaries (the “Troika”) in the proceedings of foreign national courts. The Troika comprises heads of state, heads of government, and ministers of foreign affairs (as explained by the ICJ judgment in the Arrest Warrant case). They enjoy that kind of immunity while in office; and it protects them from judicial proceedings in relation to anything they said or did in either private or official capacity—even prior to ascension to office. Personal immunity generally tends to end upon the termination of office; but in the highly criticized Arrest Warrant ruling, the ICJ appears to have held that immunity ratione personae endures even post-incumbency for Troika officials for things done or said while in office.
For its part, immunity ratione materiae is a residual kind of immunity, which non-Troika public officials enjoy from judicial proceedings in the courts of other nations for things said or done in an official capacity. The privilege is called “functional immunity” because it protects this residual class of officials only for things they say or do in the course of their functions as public officials. It doesn’t protect them for things done or said in a private capacity. As a result, this kind of immunity, unlike the personal immunity of the Troika, is not considered absolute.
In a sense, the descriptions of these immunities, according to their attributions as personal or functional, are only portmanteau references—signaling the “bottom line” of the immunity that is recognized for each category of officials. For the Troika, ratione materiae immunity is already encompassed by the broader ratione personae immunity that attaches to both official and private acts. Whereas for non-Troika officials, only ratione materiae immunity is recognized with respect to things done or said in an official capacity.
The Source of the ILC’s Muddied Waters
Fairness to the ILC requires acknowledging that the limited remit of accountability for international crimes in the national courts of other states—rejecting only immunity ratione materiae—is largely inherited from the ICJ. Notably, the current project of the ILC was inspired by the judgment of the ICJ in the case of the Arrest Warrant of 11 April 2000 (Democratic Republic of the Congo v Belgium).
The Democratic Republic of the Congo (DRC) had sued Belgium at the ICJ, urging the court to declare as unlawful in international law the arrest warrant that Belgian authorities issued against Abdoulaye Ndombasi Yerodia when he was DRC’s minister of foreign affairs. The DRC objected to the arrest warrant’s purpose of prosecuting Yerodia in Belgian national courts for crimes against humanity and war crimes. The ICJ agreed with the DRC and declared the arrest warrant invalid in international law, because Yerodia, as the minister of foreign affairs of the DRC at the time of the arrest warrant, enjoyed immunity ratione personae from prosecution in the national courts of Belgium. On the question of whether international law recognized an exception to such immunity in the context of national prosecutions for international crimes, the ICJ declared itself “unable to deduce” from the existing practice of states any exception to this class of immunity where its beneficiary is “suspected of having committed war crimes or crimes against humanity.”
Given the complexity of the ICJ judgment, including questions concerning who else might enjoy that kind of immunity as a state official, ILC members agreed that the issue of immunity of state officials in foreign criminal jurisdictions should be more clearly regulated in an international treaty. This culminated in the ILC draft text that now indicates there is no immunity ratione materiae for state officials accused of international crimes in the criminal proceedings of foreign national courts—although it leaves untouched the question of immunity ratione personae, implying acceptance of the ICJ’s assertion of its existence.
The ICJ’s decision in the Arrest Warrant case has provoked much debate. For one thing, it would have been extremely awkward—or worse—for international law to permit Belgium to prosecute in its national courts a foreign affairs minister of the same country where King Leopold is renowned to have committed some of history’s worst crimes against humanity.
Still, the paradoxical correctness of the Arrest Warrant case, in the light of that historical-political context, does not reflect the legal accuracy of the resulting jurisprudence. Critics will consider that the correctness of the ICJ’s legal reasoning in the relevant regard lacked as much substantive conviction as the phrasing of “unable to deduce” used to render it. In a commentary delivered on the heels of the judgment, Antonio Cassese, one of modern history’s most eminent international jurists, expressed “serious misgivings about some of the Court’s conclusions.”
Reexamining the Correctness of the Rule of Immunity Ratione Personae
There are a number of angles from which the ILC might have examined the correctness of the ICJ’s pronouncements in the Arrest Warrant case, to the extent that it recognizes immunity ratione personae for the Troika even for international crimes.
A Questionable Value Judgment
The ICJ rationalized its jurisprudence of absolute personal immunity for the Troika by reasoning that such immunity “protect[s] the individual concerned against any act of authority of another State which would hinder him or her in the performance of his or her duties.” In other words, immunity must be absolute, because if its intended beneficiary is “arrested in another State on a criminal charge, he or she is clearly thereby prevented from exercising the functions of his or her office.” So, the ICJ held, not even prosecution for an international crime would constitute an exception to this absolute rule of immunity.
Legal scholars—including Cassese—tend to assume that protection of a Troika official against prosecution or an arrest “which would hinder him or her in the performance of his or her duties” is too important to risk exposing him or her to the criminal processes of another state; presumably notwithstanding that such a prosecution or arrest may, say, prevent or punish an ongoing genocide in which he or she may be implicated.
But that value judgment is necessarily troubled by the fact that no human being is indispensable in the life of a nation—not even those occupying office as head of state or head of government, let alone a foreign affairs minister. A successor will always emerge to take over the reins of office in the event of death, disability, or any other eventuality that might terminate a political tenure midstream. Legal circumstances may also terminate office: A head of state may be impeached or required to serve a sentence of imprisonment following a criminal conviction under his or her own domestic law. Thus, imbuing a Troika official with immunity while in office does not recognize any distinction in what may or may not properly interfere with the supposed privilege of nondisruption of tenure.
The ICJ’s Inability to Deduce an International Crimes Exception to Personal Immunity
Another source of doubt in the Arrest Warrant jurisprudence is the ICJ’s declaration that it was “unable to deduce” from the practice of states any exception to personal immunity before a national court trying a Troika official accused of an international crime. There are important milestones in the evolution of international law that necessarily contradict this conclusion.
It is entirely correct of the ICJ to signal that its judgment does not suggest that there is immunity ratione personae for a Troika official when prosecuted before an international tribunal such as the International Criminal Court. As the court notably put it:
[A]n incumbent or former Minister for Foreign Affairs may be subject to criminal proceedings before certain international criminal courts, where they have jurisdiction. Examples include the International Criminal Tribunal for the former Yugoslavia, and the International Criminal Tribunal for Rwanda … and the … International Criminal Court[.]
Similarly, the ILC was right to make it clear that its work on the current project concerns only the question of immunity before national courts; the question doesn’t at all trouble the matter of jurisdiction of an international court. Defining the boundaries of the topic, the ILC Special Rapporteur explained that distinction as follows at paragraph 103 of his inception report:
Firstly, it concerns only the immunity of State officials from foreign criminal jurisdiction. [Emphasis received.] This means that the subject under consideration here is not immunity from international criminal jurisdiction or immunity from national civil or national administrative jurisdiction per se. Immunity from international criminal jurisdiction appears to be fundamentally different from immunity from national criminal jurisdiction. International criminal jurisdiction is of a different legal nature, as it is exercised by international courts and tribunals. These courts and tribunals are established and therefore have and exercise their jurisdiction on the basis of an international agreement or decision of a competent international organization. This means that they have a mandate from the States themselves, or, as noted in the decision of the Special Court for Sierra Leone in Prosecutor v. Charles Ghankay Taylor, from the international community. The principle of sovereign equality of States, expressed in the formula par in parem non habet imperium, which is the fundamental international law rationale for the immunity of State officials from foreign jurisdiction, cannot be the rationale for immunity from international jurisdiction. The absence of immunity of State officials from international criminal jurisdiction in the international law instruments on which the exercise of such jurisdiction is based cannot be invoked to claim that State officials therefore also do not have immunity from national jurisdiction, or as proof that they do not have such immunity.
The ILC is correct that the absence of immunity ratione personae before an international criminal tribunal in the exercise of its jurisdiction is not as such evidence of absence of immunity ratione personae before an international court. In that regard, the ILC was no doubt echoing the conclusions of the ICJ that its examination of the “the legal instruments creating international criminal tribunals, and which are specifically applicable to [them] do not enable it to conclude that any [exception to immunity ratione personae] exists in customary international law in regard to national courts.”
That, however, is not the end of the inquiry. The question remains whether there is a further basis—beyond a mere pro forma reference to the absence of immunity before an international criminal tribunal—to suggest that international law contemplates the rejection of immunity ratione personae for a Troika official charged with an international crime before a national court. That the ICJ was “unable to deduce” that indication in the practice of states is not a conclusive answer to the question. That declaration failed to account for the implications of legal developments such as the grave breaches provisions of the Convention against Genocide (1948), the Geneva Conventions (1949), Control Council Law No 10, nor the scholarship of leading jurists of international law such as Hans Kelsen.
Convention Against Genocide
Genocide is one of the cardinal crimes in international law. The Convention for the Prevention and Punishment of the Crime of Genocide provides in Article IV that persons suspected of genocide “shall be punished, whether they are constitutionally responsible rulers, public officials or private individuals.” The implication of this provision in relation to immunity ratione personae is immediately clear from Article VI, which requires that suspects of genocide “shall be tried by a competent tribunal of the State in the territory of which the act was committed, or by such international penal tribunal as may have jurisdiction with respect to those Contracting Parties which shall have accepted its jurisdiction” (emphasis added). This means that a head of state, for instance, implicated in a genocide in another country shall be liable to the criminal jurisdictions of that other country. The provision necessarily rules out immunity ratione personae for him before the national courts of the jurisdiction where he is implicated in a genocide.
Grave Breaches of the Geneva Conventions
The four Geneva Conventions contain a set of provisions generally referred to as the “grave breaches” provisions. They eponymously signify breaches that are so grave as to require criminal punishment. (See, for instance, Articles 49 and 50 of the Geneva Convention No 1.) A signal purpose of that scheme of accountability is specifically to permit prosecution of even foreign war crimes suspects in foreign national courts. (See, for instance, Article 49 of the Geneva Convention No 1.) Keeping in mind that those breaches require criminal punishment, that set of provisions similarly includes a requirement that “No High Contracting Party shall be allowed to absolve itself or any other High Contracting Party of any liability incurred by itself or by another High Contracting Party in respect of breaches referred to in the preceding Article.” (See, for instance, Article 51 of the Geneva Convention No 1, emphasis added.) Notably, that imperative of accountability was not couched with limitations recognizing immunity ratione personae for any official.
Control Council Law No 10
In the Arrest Warrant case, the ICJ stated that it “examined the rules concerning the immunity or criminal responsibility of persons having an official capacity contained in the legal instruments creating international criminal tribunals.” One of the instruments examined by the court is “the Charter of the International Military Tribunal of Nuremberg, Art. 7.” That provision clearly rejected immunity ratione personae for Troika officials in the following words: “The official position of defendants, whether as Heads of State or responsible officials in Government Departments, shall not be considered as freeing them from responsibility or mitigating punishment.” As the ICJ correctly indicated, that provision was similar in its import as “the Charter of the International Military Tribunal of Tokyo, Art. 6; Statute of the International Criminal Tribunal for the former Yugoslavia, Art. 7, para. 2; Statute of the International Criminal Tribunal for Rwanda, Art. 6, para. 2; Statute of the International Criminal Court, Art. 27.”
But, having examined those instruments, the ICJ still found itself unable “to conclude that any such exception exists in customary international law in regard to national courts.”
Regrettably, one important instrument that the ICJ failed to consider was Control Council Law No 10 (CCL10). It was a framework legal instrument that the Allied Control Council in Germany adopted on Dec. 20, 1945, for the purpose of harmonizing the prosecution of war criminals in the national zones of occupation of the Allies following World War II. It governed the prosecutions of war criminals on charges of the international crimes of aggression, war crimes, and crimes against humanity “other than those dealt with by the International Military Tribunal” under the Charter of the International Military Tribunal. Significantly, the International Military Tribunal (known colloquially as the Nuremberg Tribunal) was the international tribunal, whereas the tribunals organized under CCL10 were necessarily national tribunals.
But just as Article 7 of the Charter of the Nuremberg Tribunal rejected immunity ratione personae for even heads of state, so too did Article II(4)(a) of the CCL10:
The official position of any person, whether as Head of State or as a responsible official in a Government Department, does not free him from responsibility for a crime or entitle him to mitigation of punishment.
As with the ICJ’s omission of the preclusion of immunity ratione personae in the Convention against Genocide—and arguably also in the grave breaches provisions of the Geneva Conventions—it is indeed a significant matter for the Arrest Warrant jurisprudence to have omitted the precedent set by CCL10 precluding immunity ratione personae for Troika officials facing prosecution for international crimes before national tribunals, in a manner identical to Article 7 of the Nuremberg Charter.
Reorienting International Law Against Personal Immunity
The legal historiography of international law that culminated in the rejection of immunity ratione personae for even heads of state in both the Charter of the Nuremberg Tribunal (for the international tribunal) and the CCL10 (for the national tribunals) goes back to the international law reform that was launched in 1919 following the catastrophe of World War I. The leading nations sent their top lawyers (knowledgeable in international law) to Paris to help negotiate the settlements that culminated in what became known as the Treaty of Versailles Article 227, which provided:
The Allied and Associated Powers publicly arraign William Il of Hohenzollern, formerly German Emperor, for a supreme offence against international morality and the sanctity of treaties.
A special tribunal will be constituted to try the accused, thereby assuring him the guarantees essential to the right of defence. It will be composed of five judges, one appointed by each of the following Powers: namely, the United States of America, Great Britain, France, Italy and Japan.
In its decision the tribunal will be guided by the highest motives of international policy, with a view to vindicating the solemn obligations of international undertakings and the validity of international morality. It will be its duty to fix the punishment which it considers should be imposed.
The Allied and Associated Powers will address a request to the Government of the Netherlands for the surrender to them of the ex-Emperor in order that he may be put on trial.
Adopted by the most powerful states on earth at the time, that provision was a clear rejection of immunity ratione personae for the former German emperor. Perhaps of equal interest was the backstory of that provision, which entailed a deliberate effort to hold heads of state accountable for international crimes. British Prime Minister David Lloyd George and his French counterpart, Georges Clemenceau, led this effort; Lloyd George declared that “we are making international law.” (See Chile Eboe-Osuji, “End of Immunity: Holding World Leaders Accountable for Aggression, Genocide, War Crimes and Crimes Against Humanity.”) And Clemenceau riffed that “people everywhere would be satisfied” if the Kaiser could be prosecuted. “They will feel that justice will in future be done in the case of Kaisers and Kings just as much as in the case of common men.” That was a clear determination to apply international law to heads of state as it is applied to ordinary people.
That vision of accountability for international crimes was pursued with fervor by the legal representatives of both Lloyd George and Clemenceau in the Commission on Responsibility of the Authors of the War and the Enforcement of Penalties at the Paris Peace Conference. In it, Ernest Pollock, then serving as the solicitor general of England and Wales, represented Great Britain and the British Empire. France was, in turn, represented by University of Paris law Dean Ferdinand Larnaude. Both men were at the vanguard of a commission comprising 10 national delegations that rejected the arguments of U.S. Secretary of State and Chairman of the Commission Robert Lansing, as he insisted that the immunity of the Kaiser must be respected as a matter of international law. In the end, the commission voted 8-2 in favor of casting international law (as they did in their eventual report) to reject immunity even for “heads of state” in the following language:
[I]n the hierarchy of persons in authority there is no reason why rank, however exalted, should in any circumstances protect the holder of it from responsibility when that responsibility has been established before a properly constituted tribunal. This extends even to the case of heads of state.
The dissenting minority of two delegations—the U.S. and Japan—voted against that blueprint. However, President Wilson eventually joined Lloyd George and Clemenceau in their agreement that the Kaiser must be prosecuted; Wilson himself drafted the initial text that became Article 227 of the Versailles Treaty.
The legal reform that started in Paris in 1919 denied the plea of personal immunity to heads of state and other officials charged with international crimes before international tribunals. That outlook was apparent from Article 227 of the Versailles Treaty, which contemplated the creation of an international tribunal to try the Kaiser. So, too, were the deliberations of the Commission on Responsibilities. Similarly, the immunity-abjuring Article 7 of the Nuremberg Charter—the normative progeny of Article 227 of the Versailles Treaty—was contained in an instrument establishing an international tribunal.
As explained earlier, international law’s tendency to deny immunity ratione personae is not limited to international tribunals. There was a similar rejection of the same immunity in the national prosecutions organized under CCL10. The work of the national tribunals organized under that instrument thus suggests that national tribunals alongside international tribunals do serve as agents of the international community when engaged in seeking accountability for international crimes.
Agents of the International Community
Hans Kelsen (once described by Harvard Law Dean Roscoe Pound as “the leading jurist of [their] time”) also considered that states act as agents of the international community, rather than for their own selfish ends, when they deploy their jurisdiction to implement rules of international law. Kelsen saw international law as “primitive law”—in a continuous state of evolution toward a more efficient, centralized order of sanctions enforcement. Under this framework, Kelsen viewed reprisal as a
[U]niversally accepted and undisputed part of positive international law. Kelsen insisted that the “individual who carries out the sanction acts as an agent of the legal order. This is equivalent to saying that the individual who carries out the sanction acts as an organ of the community constituted by the legal order. … The legal sanction is thus interpreted as an act of the legal community[.]
One example of international and national tribunals as agents of the international community in the enforcement of international criminal law occurred at the end of World War II, with the jurisdiction that was conferred not only upon the International Military Tribunal at Nuremberg (by the charter of the IMT), but also upon national military tribunals of the occupied Germany (by virtue of the CCL10). The preclusion of personal immunity of Troika officials in the processes of those national tribunals—as in the international tribunal—is a clear indication of the post-World War II reform of international law, which ushered in a new order that pushed back against personal immunity of Troika officials. It falls entirely within the scope of the mandate of the ILC to give sustained value to that law reform, regardless of the inability of the ICJ to deduce that progressive trajectory in international law. It is precisely in the mandate of the ILC to lead that discussion.
***
An eminent jurist once observed that:
Law is the settled practice which by evolution and development comes when a large body of opinion in a State, by Act of Parliament, or by the changes introduced from time to time, improves, alters and develops the law. Law is not something incapable of development. The law in France, in the days of Louis XIV, is not the same as it is today. The law in the British Empire is not the same as it was in the days of Henry VIII. And we regard the occasion of the Peace Conference, with its association of, I think I am right in saying something like fifteen or sixteen countries—as an opportunity when these countries, in accord with the traditions and principles of law, may bring up to date the duties which now arise from the settled opinion of civilised States.
With those observations, the speaker declared that:
[F]or the peace of the world, it is right we should bring to trial those who are responsible for such unconscionable breaches of the principles of humanity which have been committed.
Those were the words of the U.K. solicitor general, Ernest Pollock, on March 17, 1919, during a debate at the Paris Peace Conference on the legal correctness of prosecuting the German Kaiser Wilhelm II for what are known today as international crimes. In 1919, Pollock was leading the charge of a law reform effort against a legal doctrine of impunity for heads of state charged with international crimes, at a time when the international community had not been sufficiently organized as to have an institutional framework for the harmonious updating of international law. In our own time, that institutional law reform framework now exists. The ILC occupies its center, with its mandate explicitly stated as the progressive development of international law.
Following the horrors of two world wars—which wreaked incalculable havoc on humanity in ways that severely strained the very conception of what it means to be civilized—the international order resolved to reform international law for the purpose of protecting humanity. It sought to do so by emphasizing the ethos of both human rights and accountability for their violations. Amongst the hallmarks of that development are the adoptions of the Charter of the Nuremberg Tribunal, the Control Council Law No 10, the Convention against Genocide, the Geneva Conventions of 1949, the Convention against Torture, and various international law of human rights instruments.
The central question may be: Does a rule of personal immunity for a head of state mean, as a matter of international law, that no other state is free to use its own legal processes to try and stop the head of state of another state who is committing genocide? As it goes for the prevention and punishment of genocide, so too must it for the crime of aggression, crimes against humanity, and war crimes—whether or not explicitly codified in a treaty.
And the resulting question becomes whether it now falls within the progressive mandate of the ILC to conciliate the updated international law since at least the end of World War II with the ideation of sovereign immunity that is often traced to 1812. The ILC may need to consider whether the mandate of a head of state or head of government—which is necessarily not immune to interference by sundry factors including illness, disability, death, and national impeachment—must still remain immune from the legal process of accountability in relation to international crimes, out of the concern that such a legal process might lead to an interference with the political mandate of the accused within his own state.
– Chile Eboe-Osuji was the fourth president of the International Criminal Court. He is the author of the new book “End of Immunity: Holding World Leaders Accountable for Aggression, Genocide, War Crimes and Crimes against Humanity” (2024). Published courtesy of Lawfare.