On May 9th, 2025, an international coalition of almost 40 states, senior legal experts of the European Commission, the European External Action Service, the Council of Europe, and Ukraine, together officially endorsed the creation of a Special Tribunal for the Crime of Aggression against Ukraine. This represents a significant step toward holding Russia accountable for its illegal war and violations of international law. This blog post seeks to examine in greater detail the development, structure, and prospective functioning of the Tribunal, while situating it within the broader framework of international law. In parallel, it aims to formulate policy recommendations whereby Germany might continue its active support for Ukraine in the legal domain and reaffirm its commitment to upholding the rules-based international order.
What is the Crime of Aggression?
The crime of aggression is by no means a novel concept. In 1945, the crime of aggression was prosecuted for the first time in history before the International Military Tribunal at Nuremberg. In 1974, the United Nations General Assembly adopted Resolution 3314, which defined aggression as the use of armed force by a State against the sovereignty, territorial integrity, or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations. Although resolutions of the General Assembly are not legally binding, they often carry considerable political weight. Initially, the primary purpose of this resolution was to serve as an interpretative tool for the Security Council in determining whether a State had committed an act of aggression against another. However, the resolution has reignited a debate on the recognition of individual criminal responsibility under international law for the commission of the crime of aggression. Interest in this problem has existed since at least the time of the Nuremberg Trials, but has gradually lost momentum in the intervening years.
Why do we Need a Special Tribunal for the Crime of Aggression?
The International Criminal Court (ICC) possesses jurisdiction solely over crimes committed by natural persons, irrespective of whether the individual acted in an official or private capacity. Its mandate, however, is limited to specific offences enumerated in the Rome Statute — the Court’s founding treaty — including genocide, crimes against humanity, and war crimes. Notably, the crime of aggression was not originally included as a distinct offence within the Statute. In 2010, the so-called Kampala Amendments were adopted at the Review Conference of the ICC in Kampala, Uganda. These amendments formally incorporated the crime of aggression into the body of international crimes prosecutable by the ICC through an explicit amendment to the Rome Statute. The inclusion of Article 8 bis (indicating repeated numbering for a later version of a legal article) thus marked a significant initial step toward establishing individual criminal responsibility for the crime of aggression under international criminal law. A separate provision—Article 15 bis—was also introduced into the Rome Statute via treaty amendment, setting out stringent conditions under which the Court may assert jurisdiction over the crime of aggression.
Ukraine has been a State Party to the Rome Statute since January 1, 2025 and has also ratified the Kampala Amendments, whereas Russia has yet to sign or ratify the treaty and the amendments, respectively. With respect to the crime of aggression, the ICC lacks jurisdiction over individuals who are nationals of non-State Parties. As a result, the Court is not empowered to prosecute Russian senior leaders for the crime of aggression. The sole exception would be a referral by the United Nations Security Council—an avenue that, while theoretically possible, is subject to specific legal conditions which cannot be elaborated here. Given the political deadlock over Ukraine in the Security Council, particularly due to Russia’s veto power, such a referral remains highly improbable.
However, it must not be overlooked that the ICC retains jurisdiction over other core crimes under international law. In 2023, the Court issued an arrest warrant for, among others, Russian President Vladimir Putin. He is accused, inter alia, of having committed a war crime through the unlawful deportation of Ukrainian children to the territory of the Russian Federation. The fact that the ICC does not have jurisdiction over the crime of aggression gives rise to a significant accountability gap, which could be addressed either through an amendment of the Rome Statute or the establishment of a Special Tribunal.
This post focuses on the latter approach by exploring the question of how establishing a Special Tribunal might allow Russian senior leadership to be held accountable for the crime of aggression.
A Special Tribunal on the Crime of Aggression: Historical Overview
Russia’s armed conflict against Ukraine began in 2014 with the unlawful annexation of the Crimean Peninsula, marking a clear violation of international law. However, the full-scale invasion of Ukraine in 2022 represented the tragic culmination of Russia’s hegemonic ambitions. The war has now persisted for over three years. Efforts to hold Russia accountable for the crime of aggression began as early as 2022. In addition to sustained political and diplomatic pressure, Russia has faced a wide array of economic sanctions. That same year, institutional responses were also initiated. The mandate of the European Union Agency for Criminal Justice Cooperation (Eurojust) was expanded with a view to help gather evidence on Russia’s persistent and continued violation of international law. This was carried out through the establishment of the International Centre for the Prosecution of the Crime of Aggression Against Ukraine (ICPA) as part of a Joint Investigation Team. Furthermore, the United Nations Human Rights Council created the Independent International Commission of Inquiry on Ukraine.
The potential establishment of a special tribunal was already under consideration in 2022, primarily in response to the jurisdictional limitations faced by the ICC. Even at that early stage, discussions included the possible integration of such a tribunal within the institutional framework of the Council of Europe.
At the 2023 Council of Europe Summit, the Register of Damage Caused by the Russian Aggression was established through the adoption of the Reykjavík Declaration. This register enables Ukrainian citizens and nationals to report damage to immovable property as well as the loss of close family members. It represents an initial step toward securing compensation for the injustices suffered. The envisaged next step is the creation of a Special Tribunal, intended to ensure that reparations are pursued through appropriate judicial proceedings.
A Special Tribunal for the Crime of Aggression Against Ukraine: How it would Work
The Special Tribunal has not been officially created yet. Its formal establishment through the Council of Europe depends on a specific legal process that can only begin once Ukraine’s President formally invites the Secretary General of the CoE to initiate it. This invitation is expected to be issued during the upcoming annual session of the Council of Europe’s Committee of Ministers, scheduled to take place in Luxembourg on 14 May 2025. Ukraine’s Foreign Minister, Andrii Sybiha, is expected to deliver a letter to the Secretary General, officially requesting the initiation of steps to set up the tribunal. Its creation would require a bilateral treaty under international law between Ukraine and the Council of Europe, which would provide the necessary legal foundation for its establishment.
It is important to emphasize that the envisaged tribunal is a so-called internationalized tribunal. Other such examples are the Special Court for Sierra Leone, the Special Tribunal for Lebanon or the Extraordinary Chambers in the Courts of Cambodia. While the Special Tribunal for the Crime of Aggression Against Ukraine will be grounded in Ukrainian domestic law, its procedural framework is modeled on, or directly incorporates, the procedural principles of the European Court of Human Rights. Moreover, the composition of the judiciary is intended to be international in character.
Legal Barriers: State Immunity Continues to be a Challenge when Seeking Justice
Nevertheless, the legal challenges associated with the establishment of a future Special Tribunal remain significant. As a general rule, incumbent heads of state, heads of government, and foreign ministers enjoy absolute immunity from foreign criminal jurisdiction during their term of office. This immunity applies both to acts carried out in a private capacity and to those performed in an official capacity. Even after leaving office, functional immunity continues to apply to acts conducted in an official capacity—unless the matter is taken up by an international court.
According to publicly available information on the Council of Europe’s webpage, the Special Tribunal would only be able to exercise jurisdiction over the Russian head of state, head of government and the foreign minister after their tenure or if immunity were to be waived. Nonetheless, it is crucial to establish the institutional and structural framework for the tribunal now. Importantly, proceedings in absentia would not pose a legal barrier to the work of the Special Tribunal.
Relationship with Other Courts
Another important consideration is the relationship between the proposed Special Tribunal, the ICC, and national courts, particularly those exercising universal jurisdiction.
With respect to the Special Tribunal, it is generally understood to position itself as a complementary institution to the ICC, aiming to establish a cooperative relationship where possible. The same principle applies to national courts. Cooperation is also envisaged in cases where domestic jurisdictions — especially those invoking universal jurisdiction — initiate criminal proceedings against President Putin or other senior leaders of the Russian Federation.
The advantages of the Special Tribunal are evident: its more robust institutional framework – including mechanisms such as a Register of Damage, a planned Claims Commission, a dedicated Victims’ Fund, and stable financial resources – is intended to lay the foundation for effective prosecution of high-ranking individuals responsible for the crime of aggression, notwithstanding the formal legal obstacles that may arise.
Political Implications: Effects on Peace Talks and Wider Strategic Implications
The establishment of the Special Tribunal does not necessarily conflict with potential peace negotiations between Russia and Ukraine. Rather, it serves the distinct purpose of upholding the international rules-based order and ensuring accountability for the commission of crimes that are particularly grave under international criminal law. Peace negotiations, by contrast, would primarily aim to bring about a cessation of hostilities; all further political and legal arrangements would then be subject to negotiation between the parties.
Nonetheless, the precise implications of potential criminal proceedings before the Special Tribunal against senior officials of the Russian Federation remain difficult to ascertain or predict. Following the issuance of an arrest warrant for President Vladimir Putin, among others, some critical voices expressed concern that such measures might undermine prospects for peace negotiations. However, it must be clearly acknowledged that the existence of judicial proceedings—whether before the ICC, a prospective Special Tribunal, or domestic courts—is unlikely to constitute the decisive obstacle to achieving peace between the aggressor state, Russia, and Ukraine, the victim of the aggression. Rather, it appears highly questionable whether President Putin has any genuine intention to pursue peace at all.
Given the current context—including renewed heavy fighting along the front lines and Russia’s continued and indiscriminate shelling of Ukrainian territory—genuine, credible, and sustainable peace negotiations appear distant. This makes it all the more vital to demonstrate to Russia a unified stance, marked by determination, solidarity, and a firm commitment not only to the defense of Ukraine, but also to the protection of shared values. The creation of the Special Tribunal would therefore complement military support and economic sanctions by signaling political resolve and reinforcing collective cohesion in the face of ongoing aggression.
Germany’s new Foreign Minister, Johann Wadephul, has already expressed support for this strategic initiative aimed at deterring further Russian military aggression—not only through the continued supply of weapons to Ukraine, but also by offering explicit political backing for the establishment of the Special Tribunal. While legal obstacles persist, the prospective creation of the tribunal represents an important step forward. It signals unity, resolve, and a shared commitment to the principles of international law and accountability.
Elisabeth Hoffberger-Pippan
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