A special tribunal to investigate the crime of Russian aggression against Ukraine complements existing mechanisms of justice and represents a critically important step toward upholding the principle of the rule of law in international relations and ensuring that punishment for the most serious international crimes is inevitable, according to Victoria Zagorui, an attorney at Barristers LLP.

Commenting to the Interfax-Ukraine news agency on the legal aspects of establishing the special tribunal, she noted, “The tribunal is a temporary (ad hoc) international judicial body established for a specific purpose: to investigate and prosecute those responsible for committing this key crime.” At the same time, the statute of the special tribunal specifies that the “crime of aggression” means the planning, preparation, initiation, or execution by a person who has the capacity to effectively exercise control over or direct the political or military actions of a state, of an act of aggression which, by its nature, severity, and scale constitutes a clear violation of the UN Charter.

“The need to establish such a body stems from the existence of a so-called ‘jurisdictional gap’ in international law. The main obstacle to investigating the crime of aggression in national courts or at the International Criminal Court is the immunity of high-ranking officials (heads of state, government, foreign ministers), which shields them from foreign jurisdiction while in office. "The Special Tribunal, which will act on behalf of the international community and is being established under the auspices of the Council of Europe, is designed precisely to overcome this immunity," the lawyer emphasized.

Zagorui noted that “this mechanism will make it possible to hold the highest-ranking officials of the aggressor state accountable, regardless of their current status.”

In addition, the special tribunal mechanism provides for direct and unquestionable jurisdiction over the crime of aggression, which allows for the prosecution of the leadership of the Russian Federation, despite the fact that the Russian Federation is not a party to the Rome Statute.

The special tribunal will also have international legal personality, rather than the status of a hybrid or national body, provides for the possibility of in absentia proceedings, which “allow justice to be served even if the accused are not physically present in the courtroom,” and also means that “an amnesty granted to any person falling under the jurisdiction of the special tribunal does not preclude criminal prosecution.”

“This is extremely important, as it prevents national amnesties or amnesties granted by third parties from obstructing justice for the crime of aggression. Therefore, the establishment of the Special Tribunal is a historic step that clearly establishes the liability of high-ranking officials for the crime of aggression, completely disregarding their personal immunities,” she said.

Commenting on the relationship between the special tribunal and the International Criminal Court (ICC), Zagorui noted that “these are different but complementary institutions.” Specifically, the ICC has jurisdiction over four core international crimes: genocide, crimes against humanity, war crimes, and the crime of aggression.

Ukraine has recognized the ICC’s jurisdiction over crimes against humanity and war crimes committed on its territory by submitting two declarations in accordance with Article 12(3) of the Rome Statute. This allows the ICC Prosecutor to investigate and prosecute these categories of crimes.

At the same time, the ICC’s jurisdiction over the crime of aggression is limited. According to the Kampala Amendments to the Rome Statute, the ICC may only consider this crime if both the aggressor state and the victim state are parties to the Rome Statute and have ratified these amendments, and provided that the case is referred to the ICC by the UN Security Council.

“Since neither Ukraine nor the Russian Federation has ratified the Rome Statute or the amendments regarding aggression, and since the Russian Federation, as a permanent member of the UN Security Council, has the right of veto, the ICC cannot independently initiate prosecution for this specific crime. This is precisely what creates the jurisdictional gap that a special tribunal is intended to fill. It will not duplicate the work of the ICC but will complement it, ensuring comprehensive coverage of crimes committed during the aggression,” Zagoruy explained.

She emphasized that the ICC investigates war crimes, crimes against humanity, and genocide committed on the territory of Ukraine, and this pertains to specific acts: the killing of civilians, torture, deportations, the destruction of civilian infrastructure, and so on. Both rank-and-file perpetrators and their commanders may be held accountable for these crimes.

At the same time, the special tribunal will focus exclusively on the crime of aggression—that is, on the very act of planning, preparing, initiating, and waging a war of aggression. Responsibility for this crime lies solely with the senior political and military leadership of the aggressor state.

Zagorui also noted that cooperation between the special tribunal and the ICC will be based on the principle of ne bis in idem (no one may be punished twice for the same act), which is fundamental to international law.

“A person cannot be convicted twice for the same crime. However, the same person may be convicted of different crimes. For example, a high-ranking official may be convicted by the special tribunal for the crime of aggression (for ordering the start of a war), and that same official may also be convicted by the ICC for crimes against humanity (for example, for a policy of deporting children) or for war crimes (for orders to indiscriminately shell cities),” the lawyer explained.

She noted that a special tribunal may enter into agreements or practical arrangements with the ICC to ensure the effective exercise of their respective jurisdictions. In particular, whenever a person subject to an ICC arrest warrant is detained in ICC pretrial detention facilities, the special tribunal gives priority to proceedings before the ICC.

"The courts’ activities will be coordinated to ensure comprehensive justice and full accountability for all categories of international crimes. Focusing exclusively on the crime of aggression, the tribunal aims to hold the senior leadership of the Russian Federation accountable—those responsible for the very decision to start the war. For victims of the war who have suffered from specific crimes, such as destruction of property or unlawful detention, the mechanisms of justice remain the national courts of Ukraine and the ICC, which are already actively working to document and investigate these crimes," Zagorui emphasized.