(Editor’s note: This article is part of Just Security’s Symposium, International Law in the Face of Russia’s Aggression in Ukraine: The View from Lviv.)

Discussions on prosecuting the crime of aggression began shortly after Russia’s full-scale invasion of Ukraine. Two years later, Ukrainian prosecutors have almost one hundred aggression cases pending against Russian officials. A coalition of States known as the Core Group of Friends of Accountability is negotiating the creation of a special tribunal that could prosecute the masterminds of the invasion. And there are efforts underway to amend the Rome Statute’s restrictive jurisdictional regime, which prevents prosecutions of Russian actors for the crime of aggression before the International Criminal Court (ICC). In short, much progress has been made since February 2022 in terms of securing justice for Russia’s invasion of Ukraine. However, challenges remain, and there are false dilemmas that need to be discussed openly going forward. Drawing on conversations with Ukrainian and international experts gathered in Lviv from Dec. 7 to 10, this article takes stock of developments and looks to the future.

Domestic Versus International Prosecutions

Negotiations on a possible ad hoc special tribunal for the crime of aggression have garnered the lion’s share of (international) attention in the last 24 months. However, during this time, Ukrainian prosecutors have pressed ahead with domestic investigations. Under the Ukrainian criminal code, the crime of aggression is prohibited by article 437, which covers “the planning, preparation, initiation and conduct” of aggressive war, as well as “participation in conspiracy aimed at commission” of such actions. Unlike the Rome Statute, the Ukrainian criminal code does not specify a leadership requirement, which suggests that this crime could be committed by anyone. In particular, it has been accepted by Ukrainian courts and scholars that at least the conduct of aggressive war as an actus reus can be committed by even ordinary fighters.

Prior to the full-scale invasion, national courts had decided a few cases on the crime of aggression. All of them focused on low-level perpetrators and ordinary fighters (see for example here, here, or here). There were some attempts to change Ukraine’s legislation and bring it in compliance with international standards, resulting in the adoption by the parliament of the law in May 2021, which introduced the leadership requirement modeled on the Rome Statute into the domestic definition of the crime of aggression. This draft, however, have not been signed into law by the President and, thus, has not yet entered into force.

Nevertheless, Ukrainian prosecutors seem to have aligned prosecutorial practice with the Rome Statute by applying article 437 narrowly. On Mar. 17, 2022, a few weeks into the full-scale invasion, the Office of the Prosecutor General of Ukraine (OPG) sent a guidance note to all prosecutors concerning the application of international humanitarian norms on the status of POWs and its effect on the criminal qualification of their actions. The note stated that POWs, as long as they do not commit other crimes, enjoy combatant immunity and should not be prosecuted for mere participation in hostilities.

More recently, on Feb. 28, 2024, Ukraine’s Supreme Court delivered a decision in a case under article 437 clarifying that the crime of aggression can be committed only by persons who are “able to exercise effective control over political or military actions of a state and/or significantly influence political, military, economic, financial, information and other processes in their own state or outside its borders, and/or manage specific directions of political or military actions.” The decision further states, by way of illustration, that such persons could be heads of States and governments, members of parliament, leaders of political parties, diplomats, heads of special services, military commanders, or heads of State bodies.

According to the OPG, at the time of writing, there are 99 criminal cases registered pertaining to Russian aggression against Ukraine. These cases include 689 suspects, among whom are the Russian ministers of defense and internal affairs, the chief of Russia’s general staff and more than 30 other high-level military commanders, all the deputies and senators of the State Duma, the directors of the foreign intelligence service and of the federal security service (FSB), and other high-level State officials. Most controversially, among the suspects are more than 30 instigators of war and propagandists of the Kremlin. This group includes famous Russian singers, TV hosts and journalists, rectors of Russian universities, as well as the patriarch of the Russian Orthodox Church. At any rate, Ukraine’s domestic prosecutions – many of which would be expected to take place in absentia (without the presence of the accused) – set an important precedent for how the crime of aggression can be handled at the national level, potentially contributing to the formation of customary international law in an area that has seen little activity in the last one hundred years.

In this regard, it is equally noteworthy who is not among the suspects in these aggression cases. The list does not include Russian President Vladimir Putin, Prime Minister Mikhail Mishustin, and Foreign Minister Sergey Lavrov. This indicates that Ukraine fully accepts the personal immunities of the troika before its national courts. At the moment, very little attention in Ukraine is devoted to the relationship between domestic aggression cases and prosecutions before a possible international tribunal. The discussions mostly revolve around the need to set up a special tribunal and what its optimal model would be. What is clear, however, and generally accepted, is that the personal immunities of the troika cannot be overcome at national level, which suggests that at least the cases against the troika should be dealt with outside Ukraine’s ordinary justice system.

An Ad Hoc Tribunal and Global Perceptions of the Russo-Ukrainian War

Since Russia’s 2014 intervention in Crimea and its eastern territories, Ukraine has faced the daunting task of holding to account the leadership of a U.N. Security Council permanent member. While this would be a tall order under any circumstances, the past two years have seen significant developments, with growing momentum behind efforts to revive the crime of aggression at the international level (in addition to domestic prosecutorial action). On one hand, the Ukrainian government has spearheaded negotiations on an ad hoc special tribunal to overcome the ICC’s jurisdictional constraints with respect to aggression on Ukrainian territory. On the other, diplomatic efforts are underway to amend the Rome Statute’s jurisdictional regime that prevents ICC prosecutions in the first place.

Nevertheless, two years later, both initiatives face headwinds due to a mix of legal and political obstacles. While the Core Group of Friends of Accountability, which now comprises 40 States, holds regular diplomatic meetings to discuss the proposed special tribunal (most recently in Vienna), negotiations have recently become bogged down in disputes over institutional design. Specifically, the definition of the crime of aggression and the (non-)applicability of the troika’s immunities have emerged as flashpoints, with Western States in the G7 advocating a hybrid tribunal grounded on Ukraine’s domestic jurisdiction while Eastern European States, led by Ukraine, favor an international tribunal, ideally created pursuant to a U.N. General Assembly recommendation. Crucially, only the latter model is likely to enjoy the power to override Putin, Lavrov, and Mishustin’s personal immunities. Negotiations continue on this and other points of contention, with most Core Group members remaining uncommitted to either model or open to a compromise solution.

At first glance, divisions between the West and East over the tribunal’s institutional design, including its ability to override the troika’s immunities, may seem like technical lawyerly disputes among (groups of) States. In fact, the debate over how to prosecute this instance of putative aggression raises fundamental questions about the ad hoc tribunal’s legitimacy to pronounce on the guilt of a permanent Security Council member and its relationship to the ICC, which in turn goes to the purposes of international law as a normative system capable of holding the most powerful actors to account. There has been much discussion of double standards, leveled mainly at Western States, with critics pointing to other cases of putative aggression that were never adjudicated, like the 2003 invasion of Iraq, to suggest that a tribunal for only the Ukrainian situation would exacerbate (rather than decrease) the selectivity of international prosecution, and delegitimize international criminal law going forward. Some emphasize that that longer-term prospective reform of the Rome Statute should take precedence over Ukraine’s immediate demands for justice, or that Ukrainians should get justice only if other victims receive the same treatment.

While there is justified concern at double standards in global affairs, some Ukraine-related commentary risks throwing the baby out with the bathwater, with critiques of the ad hoc tribunal oversimplifying global divisions over the Russo-Ukrainian war and misapprehending the stakes of the ongoing conversations. Echoing Russia’s arguments about a civilizational conflict between the West and the Rest, there has been a tendency to analyze the Russo-Ukrainian war and efforts to prosecute Putin as an example of (normative) splits between the West and the Global South. This overlooks that Ukraine, which defies categorization as part of either “the West” or the “Global South”, is embedded in a locale that cannot be disentangled from its history of colonial subjugation by Russia, anti-Slavic racism in Europe, and broader anti-imperial struggles against international law’s selectivity in Eastern Europe. Yet the assumption driving some critiques seems to be that divisions over the tribunal are best explained by normative concerns over “Western double standards,” rather than a mix of political, legal, and historical factors, including non-Western States’ economic self-interest, strategic dependency on Russian aid and arms, hegemonic regional aspirations (e.g. by China and India), and an ahistorical amnesia of Russian imperialism in the “Global East”. Likewise, while non-Western States are not in the driver’s seat in negotiations on the ad hoc tribunal, it is worth interrogating the assumption that should this be the case in Ukraine. After all, international criminal law – like human rights protection – has often developed through regional initiatives that then diffuse norms beyond their source.

With negotiations on the ad hoc tribunal inching forward, it may be time to enrich the debate over Western double standards and ask better questions than why the “Global South” does not support Ukraine. In particular, it may be worth pausing and considering the wider normative stakes and opportunities of the ongoing debates over the crime of aggression. What precedent will be set if Russia’s invasion is met with inaction or apathy? How does the prospect of continued post-colonial impunity in Eastern Europe interact with accountability demands in other regions with histories of imperialism? How does the ad hoc tribunal impact efforts to re-negotiate the Kampala amendments in the Rome Statute?

It is important to avoid false dilemmas in answering these questions. Notwithstanding Soviet support for anti-colonial struggles against Western empires, accountability for Ukrainians – subject to Russian imperial domination for centuries – will begin to remedy the impunity of a non-Western empire rather than exacerbate double standards in international law. Likewise, the prospect of accountability for aggression against Ukraine will matter most for smaller and weaker States in the global order – in both the Global South and Global East, where both Western and non-Western empires have long histories of territorial expansion. It should not be lost on anyone that Western powers have vocally opposed an international tribunal with the power to override the troika’s immunities. As analysts have observed (see here and here), the United States and UK’s preferred alternative, a hybrid tribunal, could help ensure that their leaders will never be held to account in cases of legally questionable interstate uses of force, effectively insulating them from aggression prosecutions in the future.

Given the wide range of stakeholders and different normative interests, diplomats should remain flexible on the ad hoc tribunal’s institutional design, including about the meaning of labels like “international” or “hybrid” which are ultimately open to judicial interpretation. However, observers must also remain clear-eyed about some legal questions. Is enshrining immunity for State leaders beneficial to smaller and weaker States in the global order that harbor no expansionist ambitions? By the same token, what institutional arrangements in the ad hoc tribunal’s statute have greater potential to shape the parallel negotiations on Rome Statute amendments? While there may be no obvious answers now, lawyers and diplomats would be well advised to move beyond mainstream narratives and build the future of international law with a creative eye.

Strengthening Ukraine’s Negotiating Position

While Ukraine depends on like-minded States in the process of establishing a special tribunal, there are things it can do to garner broader international support for its preferred normative positions. Most importantly, Ukraine should finally ratify the Rome Statute. This has been advocated by Ukraine’s civil society and international actors for a long time. It is also an obligation Ukraine took upon itself under article 8 of the Ukraine-EU Association Agreement.

Ratification of the Rome Statute will be not only a symbolic step to solidify Ukraine’s commitment to justice; it will also have concrete positive impact and consequences. In doing so, Ukraine will ensure its accountability efforts are globally perceived with greater credibility and legitimacy. The ICC has already issued arrest warrants for Putin, children’s rights commissioner Maria Lvova-Belova, and two high-level military commanders, yet Ukraine’s officials occasionally urge the ICC “to step up its efforts” on Ukraine. This might seem like a selective position, given Ukraine’s reluctance to join the Court.

Equally important, by ratifying the Rome Statute, Ukraine will be able to spearhead the process of amending the ICC’s restrictive jurisdictional regime on the crime of aggression. While at the moment the special tribunal is a more efficient option to ensure accountability for Russian aggression, Ukraine should in parallel lead the process towards a more permanent solution by advocating for the ICC’s expanded jurisdiction on aggression. In this way, the country’s efforts to ensure support for the special tribunal might be perceived more positively by non-European actors and not as just a “selective” quest for an ad hoc tribunal for Ukraine.


The crime of aggression is sometimes referred to as “the mother of all crimes.” However, no international tribunal has prosecuted it since Nuremberg and there are very few cases decided on the national level. Unfortunately, Russia’s horrific war against Ukraine means its lawyers are now at the forefront of developing the domestic case-law on the crime of aggression. Ukraine is also at the center of discussion on a new international tribunal with jurisdiction to prosecute the highest Russian officials for the crime of aggression.

To be sure, these discussions are complicated. There is no common position among Ukraine’s allies or advocates of accountability for aggression, while some actors worry about perceptions of “selective justice” and the tribunal’s legitimacy. As we argue in this article, accountability efforts for Russian aggression against Ukraine should be analyzed in light of these two States’ complex history and should carefully consider States’ normative expectations of the crime of aggression, especially in the Global South and Global East with histories of subjugation by empires. At the same time, Ukraine should work to improve its negotiating position by ratifying the Rome Statute and leading the process of re-negotiating the Kampala amendments.

The views expressed in the article belong solely to the authors and do not necessarily represent the position of any institution with which the authors are affiliated.

IMAGE: A destroyed window of the Roman Shukhevych museum is seen on March 5, 2024 in Lviv, Ukraine. (Photo by Stanislav Ivanov/Global Images Ukraine via Getty Images)