The founding agreement that gives the Special Tribunal for the Crime of Aggression against Ukraine its governing body was signed in Chișinău on 15 May, when 36 states and the European Union approved an Enlarged Partial Agreement at the 135th Session of the Council of Europe's Committee of Ministers, hosted in Moldova. It was the last document the tribunal needed before it can open.

Thirty-four Council of Europe member states, plus Australia and Costa Rica, joined the EU as participants. The agreement defines the composition, powers, and procedures of the Management Committee, the body responsible for appointing judges and prosecutors, approving the tribunal's budget, and governing its internal rules. Without it, none of that could happen.

It is the third founding document of a court that will be, when it opens, the first international tribunal with jurisdiction over the crime of aggression since Nuremberg and Tokyo.

"The Special Tribunal represents justice and hope," said Council of Europe Secretary General Alain Berset. "The time for Russia to be held to account for its aggression is fast approaching."

Ukraine's Foreign Minister Andrii Sybiha called 15 May a point of no return. "Very few believed this day would come," he said. "But it did." He also called on the coalition to widen:

"We need this tribunal to be global in nature. At present, it is no longer limited to Europe. This is very important for justice and the inevitability of punishment."

The Special Tribunal exists because of a jurisdictional gap that no existing court could fill. The International Criminal Court has authority over war crimes, crimes against humanity, and genocide in Ukraine, but it cannot prosecute the crime of aggression against Russia, because Russia never ratified the Rome Statute and no UN Security Council referral is possible, Russia holds a permanent veto. The crime of aggression, defined in international law as the decision by a state's leadership to wage war against another state in violation of the UN Charter, was left without a court. This tribunal is the answer to that gap.

Under the Nuremberg Charter, the crime was then called "crimes against peace," and the Nuremberg International Military Tribunal described it as the "supreme international crime" because it contains within itself the accumulated evil of the whole. No court has exercised jurisdiction over the crime of aggression since those postwar tribunals ended in 1948. The Chicago Journal of International Law and the Council of Europe's own legal directorate both characterise this tribunal as the first such institution in the more than seventy years since.

Iryna Mudra, Deputy Head of the Ukrainian Presidential Office responsible for international accountability, said signing the agreement "makes the launch of the tribunal irreversible." The advance team has been working across The Hague and Strasbourg since February 2026, preparing premises and laying the administrative groundwork. The EU has committed €10 million to support its operations. Full operations, including the appointment of 15 judges, the adoption of procedural rules, and the opening of formal investigations, are expected to begin in 2027.

The tribunal will not be able to charge a sitting head of state, head of government, or foreign minister. Vladimir Putin, Prime Minister Mikhail Mishustin, and Foreign Minister Sergei Lavrov are each protected by that provision for as long as they remain in office. The rest of Russia's senior military and political command structure carries no such protection.

Prosecutors are not waiting for the tribunal to open to gather evidence. The International Centre for the Prosecution of the Crime of Aggression against Ukraine, based at Eurojust in The Hague, has been building its case with prosecutors from Ukraine, Lithuania, Estonia, Latvia, Romania, and Poland. At a meeting in October 2025, Ukraine's Prosecutor General Ruslan Kravchenko confirmed that "the evidence collected and the materials prepared" are intended to transfer directly into the future tribunal's prosecutorial work.

The tribunal operates within the Council of Europe's institutional framework and is complementary to the ICC. The two courts are expected to sign mutual co-operation agreements, and where the ICC detains a relevant individual first, it takes procedural primacy. The Chișinău agreement now allows participating states to begin their domestic ratification processes, which must be completed before the convention formally enters into force. Some participating states have not yet finished those procedures.

Russia has already said it will treat the tribunal's decisions as "null and void." International criminal tribunals function without the co-operation of the state whose leaders they are investigating. The Nuremberg and Tokyo tribunals did not require Germany or Japan's agreement to proceed either.

The Council of Europe's parallel Register of Damage, which records compensation claims from the war, has received more than 34,000 submissions.