Ця стаття також доступна українською мовою тут.

[Editor’s Note: This article is part of a Just Security series, Prosecuting the Crime of Aggression Against Ukraine. All articles in the series can be found here.]

The last two weeks have brought promising news that the Ukrainian effort to turn back the Russian army is, miraculously, beginning to succeed. The possible shift in the war brings renewed urgency to a conversation that began shortly after the war started — how to bring accountability for the crime of aggression committed in launching the war in February 2022 and in continuing to pursue the military campaign in clear violation of the prohibition of the use of force in Article 2(4) of the United Nations Charter.

This article is the first in a series based on a meeting held in the summer of 2022 at the Yale Club in New York City that aimed to generate a detailed and concrete proposal for a tribunal to try the crime of aggression in Ukraine. The Chair’s summary provides an overview of the meeting – which was hosted by the Permanent Mission of Liechtenstein to the U.N. and the Permanent Mission of Latvia to the U.N. and attended by representatives of the Government of Ukraine as well as a number of other U.N. Member States, academics, and members of civil society.

In this series, several of the meeting participants elaborate how the Government of Ukraine and the United Nations could work together to create a tribunal. I begin this series by exploring the case for creating an international tribunal and specifically for doing so through an agreement with the United Nations, acting on the recommendation of the General Assembly. In the next three articles, Astrid Reisinger Coracini, Jennifer Trahan, and former U.S. Ambassador-at-Large for War Crimes Issues David J. Scheffer will discuss the features of a potential tribunal. Together, these articles offer a template that could form the foundation for a new international tribunal. Finally, Claus Kreß, special advisor to the ICC prosecutor on the crime of aggression, writing in his personal capacity, will conclude the series.

The Importance of Prosecuting the Crime of Aggression

The stakes of the current conflict are extraordinarily high. When Russia launched its war against Ukraine in February 2022, it began the largest cross-border land war in Europe since World War II. This follows on the illegal annexation of Crimea by Russia in 2014, the first conquest of territory in Europe since World War II. These acts stand as a blatant challenge to the global prohibition on the use of force and territorial conquest.

The United Nations Charter that was created at the close of World War II to maintain and sustain international peace places the prohibition on the use of force at its core. Article 2(4) provides: “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.” While this prohibition on war has certainly not been perfectly observed, it has contributed to an extraordinary reduction of interstate wars in the postwar era and has made the conquest of territory, which was once common, exceedingly rare. It has enabled trade and growth throughout the globe without fear that the gains will simply become spoils in war. And it has allowed small States that would once have had to fear for their existence to instead survive unmolested. This is no small reason that the number of independent sovereign States has grown roughly threefold from the end of the war to today.

Russia’s invasion of Ukraine, aided by Belarus, does not just represent the blatant violation of a rule of international law; it represents a threat to the foundational principle that underpins the modern legal order. This is why the global response to the war has been so robust, with States coalescing together to provide arms and other supplies to Ukraine. And it is why that effort must be followed by the criminal prosecution of those most responsible for the crime of aggression.

The crime of aggression was first prosecuted in an international court in the wake of World War II in what would become known as the International Military Tribunal at Nuremberg. The allies charged 24 German political, military, and economic leaders with advanced planning of an aggressive war “in violation of the terms of the Kellogg-Briand Pact of 1928” — the treaty that first outlawed war and thereby set the stage for Article 2(4) of the U.N. Charter. In its judgment, the Nuremberg court declared, “To initiate a war of aggression . . . is not only an international crime; it is the supreme international crime differing only from other war crimes in that it contains within itself the accumulated evil of the whole.”

That powerful sentence captured an essential fact about the crime of aggression — in war, the crime of aggression is the international crime from which all others flow. Were it not for the illegal aggression against Ukraine, there would be no crimes against humanity, no war crimes, and no genocide. It is, moreover, an attack not just on the country that suffers the physical attack, but an attack on the international community as a whole. This is why establishing a forum to punish such crimes is so essential.

And yet there is no international court with jurisdiction over the crime of aggression against Ukraine. Ukraine, Russia, and Belarus are not parties to the Rome Statute, which created the International Criminal Court (ICC) and gives it jurisdiction. Normally that would mean that the ICC would not have jurisdiction over the events taking place in Ukraine. However, Ukraine submitted to the jurisdiction of the court in 2014 and extended that submission indefinitely in 2015. Based on these submissions, the court can hear cases of genocide, crimes against humanity, and war crimes committed in Ukraine and the prosecutor has begun investigations of those crimes. Yet, due to a political compromise, the crime of aggression is different: unlike the other three crimes in the Rome Statute, the crime of aggression may not be prosecuted against nationals of non-state parties – including Russia and Belarus. While there are proposals to amend that provision, any amendment is likely to take at least a year if it happens at all. And even if made, the revision would most likely apply prospectively, not retroactively. Thus, international accountability for the crime of aggression against Ukraine almost certainly requires creating a new international tribunal.

The Case for Creating the Tribunal through an Agreement Between Ukraine and the United Nations

The Yale Club meeting offered a proposal for creating a tribunal to try the crime of aggression through an agreement between Ukraine and the United Nations, on the recommendation of the General Assembly.

This is far from the only proposal to create a tribunal to try the crime of aggression in Ukraine. One of the earliest, from former U.K. Prime Minister Gordon Brown, called for the creation of a special tribunal that nations could join in a kind of ad hoc legal “coalition of the willing.” Philippe Sands has been working with European lawmakers to create a tribunal in Europe. Just recently, the Council of Europe adopted a decision endorsing accountability for the crime of aggression. The Public International Law & Policy Group (PILPG) has proposed a draft law for a Ukrainian High War Crimes Court, a specialized court within the domestic Ukrainian judicial system, to prosecute atrocity crimes — including the crime of aggression — not prosecuted at the ICC. The Open Society Justice Initiative has drafted a model indictment that could be used in a number of fora. And there is a proposal similar to the Yale Club’s from the Ukraine Task Force of the Global Accountability Network that proposes a U.N. General Assembly resolution and a statute for a special tribunal formed by the U.N. and Ukraine.

There are several essential features of a new tribunal that some, but not all, of these existing proposals share with the Yale Club proposal. Here I review the elements of a tribunal that many of those who took part in the Yale Club discussion consider essential features of a new tribunal.

Three Essential Features of a New Tribunal

Feature 1: The tribunal should be international. 

Most of the proposals mentioned above call for an international tribunal, rather than a domestic one, a key distinction for several reasons. The first is symbolic and expressive: Russia’s war of aggression has harmed not just Ukraine but the international community as a whole. The second is practical: there are immunities that would likely interfere with domestic prosecution of a small number of Russian and Belarusian officials, including President Vladimir Putin, that would not apply in an international court. Hence, even though Ukrainian law (and other States’ domestic law) permits prosecution for the crime of aggression in a domestic court, cases against those most responsible for the war would be difficult, if not impossible, to pursue successfully without violating key international legal rules on immunity. (For more on immunity, see Claus Kreß’s Occasional Paper on ICC Appeals Chamber’s Judgment of 6 May 2019 in the Jordan Referral re Al-Bashir Appeal and Commentary on personal immunity (beginning on page 2626). Jennifer Trahan’s article in this series will address immunity issues more fully).

The third reason, and perhaps the most important though the least understood, is Ukrainian law, specifically the Ukrainian Constitution. As Ukrainian lawyer Alexander Komarov and I wrote several months ago, Article 125 of the Ukrainian Constitution states that, “The establishment of extraordinary and special courts shall not be permitted.” We explained that this prohibition requires that any new tribunal must be international. The tribunal should also be explicitly auxiliary, not complementary, to the domestic courts (to avoid conflict with Article 124 of the Ukrainian Constitution). Indeed, no matter which proposal moves forward, the world must not encourage casual disregard for the constraints of the Ukrainian Constitution, particularly at this moment of extraordinary transformation for Ukraine.

Feature 2: The tribunal should be created through an agreement between Ukraine and the United Nations, on the recommendation of the General Assembly.

Proceeding through the U.N. General Assembly would make good on a promise that 140 States implied when they voted in favor of a Resolution deploring the “aggression” by Russia “in violation of Article 2(4) of the Charter.” Only five States, including Russia, voted against it. Proceeding through the General Assembly, rather than an ad hoc coalition of States or a European institution, would allow States from around the world to participate in and reaffirm the foundational norm that Russia has violated. This would send a powerful message that the crime of aggression is a crime whether committed in Europe or elsewhere. Indeed, a key purpose for prosecuting the crime of aggression is to repair an international system that Russia has now damaged and to signal to all countries that they must not follow in Russia’s footsteps. That repair is limited indeed if it applies to Europe alone.

There are precedents, most notably the Extraordinary Chambers in the Courts of Cambodia (created pursuant to the recommendation of the General Assembly) and the Special Court for Sierra Leone (created pursuant to the recommendation of the Security Council, not acting under its Chapter VII authority to address threats to peace, breaches of the peace, and acts of aggression). While the General Assembly does not have the power to impose a tribunal on Ukraine (because it lacks such enforcement powers, which reside in the Security Council), it can authorize the Secretary General to work with Ukraine to establish a tribunal to which Kyiv voluntarily consents through an international agreement.

There is yet another reason to conclude the tribunal as an agreement between Ukraine and the United Nations: As Kamorav and I have explained, the Law of Ukraine on International Treaties provides that a treaty between Ukraine and the U.N. might be made subject to ratification by the Verkhovna Rada (Parliament) of Ukraine and thus become “part of the national legislation of Ukraine.” It would also be possible for the President to seek an ex ante determination by the Constitutional Court of Ukraine that the agreement is consistent with the Constitution, thus putting any constitutional doubts to rest.

Feature 3: The tribunal should be limited in scope

Any new international tribunal must be narrowly focused on the key violations that fundamentally challenge the international legal order that will likely otherwise go unpunished. This means that crimes that can be prosecuted in the ICC or in domestic courts should not be within the jurisdiction of a new international tribunal. Rather, the tribunal should be narrowly focused on the crime of aggression alone — and it should focus only on those in leadership positions. To this end, the new tribunal should adopt the definition of the crime of aggression in the Rome Statute, which limits the scope of the prosecutable offenses to “manifest” violations of the United Nations Charter and to crimes committed by those in a leadership role, specifically “the planning, preparation, initiation or execution, by a person in a position effectively to exercise control over or to direct the political or military action of a State.”

Russia’s invasion of Ukraine has put the international legal order in peril. A tribunal with these features would help to repair the damage by reinforcing for the world the foundational importance of the prohibition on use of force.

Image: Attendees of a General Assembly meeting stand in silence during a tribute to Britain’s Queen Elizabeth, at the United Nations headquarters in New York on September 15, 2022. (Photo by Ed JONES / AFP) (Photo by ED JONES/AFP via Getty Images)