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.]

In Part I of this series, Oona Hathaway explained the imperative to prosecute the crime of aggression committed against Ukraine, and the need to do so through an international criminal tribunal established through the United Nations General Assembly. In Part II, I address issues of jurisdiction and composition of a Special Tribunal for the Crime of Aggression (STCoA).

Ukraine must decide whether to request the establishment of a STCoA. A formal communication from the Government of Ukraine to the U.N. would be the first step to start the process. As Part I explains, the U.N. General Assembly could recommend the creation of the tribunal, while an agreement negotiated between the U.N. and Ukraine would resolve the details of its statute. The following proposals, previously introduced at the Yale Club roundtable meeting on June 22, 2022 (Chair’s Summary) are understood as a starting point for such discussions. They are guided by considerations of consistency, simplicity, and legitimacy. Drawing from past and present experiences assures consistency with fundamental principles of international criminal law and existing institutional frameworks. A narrowly defined jurisdiction and simplicity in an institutional structure would keep it lean and efficient. An international criminal tribunal recommended by the U.N. General Assembly would also carry the greatest legitimacy. It would best express the ideal of an international tribunal enforcing international criminal law, the criminal law of the international community as a whole.

The STCoA would be an important component in the institutional framework providing justice for Ukraine. However, it will not be able to disguise the root cause of its (proposed) existence: the overly restricted jurisdictional regime of an existing permanent International Criminal Court (ICC) that has subject matter jurisdiction over the crime of aggression, and that has temporal, personal and territorial jurisdiction over the situation in Ukraine, but that is unable to prosecute the crime of aggression in this very situation. This impunity gap can only be closed through including the crime of aggression within the default jurisdictional regime of the ICC. States should use the mandatory review of the Kampala amendments in 2025 to this end (RC/Res. 6, para. 4). Creating a STCoA and amending the ICC’s jurisdictional regime are not mutually exclusive and States should pursue both in parallel.

Jurisdictional Considerations

1.     Subject Matter Jurisdiction

a.     Limitation to the Crime of Aggression

The STCoA would have jurisdiction over one category of crime: the crime of aggression.

There are several reasons for such limited subject matter jurisdiction. First, it would emphasize the supplementary role of the STCoA vis-à-vis the ICC. The raison d`être of a special tribunal is to fill a gaping hole in the enforcement of international criminal law in the situation of Ukraine that stems from the restricted jurisdictional regime of the ICC over the crime of aggression (see Arts. 15bis, 15ter ICC Statute; and this article for details). The tribunal’s role should not go beyond this. The exercise of ICC jurisdiction over war crimes, crimes against humanity, and genocide, in the situation of Ukraine would not be limited in any way.

Instead, this solution would emphasize the central role of the ICC in the prosecution of core international crimes. This design would also respect the primary role of States to prosecute these crimes under the ICC’s complementarity principle.

Finally, a narrow jurisdiction has budgetary advantages. The preparation of a case concerning the crime of aggression is based on a different set of conduct and evidence than a case concerning war crimes, crimes against humanity, or genocide. A broader subject matter jurisdiction of the special tribunal would require disproportionally greater resources. What’s more, parallel investigations of those other crimes would needlessly duplicate efforts at the ICC and unnecessarily expend resources at both institutions.

b.     Definition of the Crime

The crime of aggression has been ongoing against Ukraine. The STCoA would therefore not only have prospective jurisdiction for the continuing crime but could be competent to cover events that started in 2014 (see temporal jurisdiction below). This has implications for the definition of the crime of aggression used in the Statute.

The principle of non-retroactivity requires that a person can be held criminally accountable only for conduct that constitutes a criminal offense at the time when it was committed (see Art. 15 ICCPR). Using the definition from Article 8bis ICC Statute in the Statute of the STCoA would easily satisfy this requirement.

The prohibition and criminalization of aggression involve rules that are beyond any doubt part of customary international law. This is true for the customary nature of the prohibition on the use of force, the principle of individual criminal responsibility for serious violations of international law, and the crime of aggression (see e.g. chapter 18 hereand Kress, chapter 14 here). The elements of the crime of aggression as defined in Article 8bis are well established in statutory criminal definitions on national and international levels (the leadership element and individual conduct). The understanding of aggression, the collective act underlying the crime, has remained virtually unchanged in GA Resolution 3314 and Article 8bis(2) of the ICC Statute since it was first introduced by a Soviet diplomat in 1933 and was found to reflect customary law by the International Court of Justice (Nicaragua v. United States 1986 Judgment, para. 195, a minore ad maius). Finally, and in order to codify a narrow definition of the crime, a threshold clause confines the scope of individual criminal responsibility vis-à-vis unlawful acts of aggression. The result is a particularly narrow definition that is difficult to meet. Still, there seems to be convincing evidence that the acts of aggression committed against Ukraine would fall within the scope of Art. 8bis ICC Statute (see e.g. Open Society Justice Initiative, Model Indictment for the Crime of Aggression Committed Against Ukraine

Article 8bis of the ICC Statute was drafted on a broad basis. The special working group on the crime of aggression was open not only to states parties of the ICC Statute but to all states on equal footing (ICC-ASP/1/Res.1). Non-states parties, including the Russian Federation, participated in these negotiations. The definition was endorsed by the special working group, adopted by consensus at the Kampala Review Conference, ratified by 43 states and implemented into various national criminal codes (see chapter 32 here). It is a solid basis for the definition of the crime of aggression in the Statute of a STCoA.

2.     Temporal Jurisdiction

The decision of whether to commence the STCoA’s temporal jurisdiction in February 2014 or February 2022 is guided by different policy considerations. The swift and strong reaction of the international community after the February 2022 acts of aggression is unprecedented (U.N. GA Res ES-11/1). This may feed the expectation that the 141 States that unequivocally condemned acts of aggression by the Russian Federation and Belarus would also support the establishment of an accountability mechanism to hold individuals criminally responsible for these acts. Also, from a budgetary point of view, focusing on the most recent acts of aggression may have its merits. Fewer acts of aggression would require less resources to investigate and prosecute. From a criminal policy point of view, on the other hand, it is inconceivable to separate these events. The crime of aggression is a continuing crime that started with the first use of force by the Russian Federation against Ukraine in February 2014 (Council of Europe, Parliamentary Assembly Resolution 1988 (2014); U.N. GA Res 68/262). It was continuing in February 2022 when the Russian Federation and Belarus committed additional acts of aggression (U.N. GA Res ES-11/1, paras. 2 and 10). It is continuing and will continue until the use of force comes to an end and the sovereignty, territorial integrity and political independence of Ukraine is restored. These acts are inseparable and form one situation, which also corresponds to the temporal scope of the situation of Ukraine before the ICC.

The STCoA’s temporal jurisdiction must also account for the tribunal’s competence to establish individual criminal responsibility for the planning and preparation of any act of aggression. If the date on which a specific act of aggression was committed triggers the tribunal’s jurisdiction, there should be consideration of whether the temporal jurisdiction sufficiently encompasses the planning and preparation of that specific act.

Since the crime of aggression is ongoing, the tribunal’s temporal jurisdiction should be open-ended.

3.     Personal Jurisdiction

The STCoA would have jurisdiction over natural persons (see also Art. 25 ICC Statute, Art. 6 International Criminal Tribunal for the former Yugoslavia (ICTY) Statute, Art. 5 International Criminal Tribunal for Rwanda (ICTR) Statute, Art. 6 Special Court for Sierra Leone (SCSL) Statute). The Statute would not require a further definition of the tribunal’s personal jurisdiction.

At the same time, the Statute would contain two inherent limitations on personal jurisdiction. First, the leadership element of the crime of aggression influences the personal reach of the tribunal. Only “a person in a position effectively to exercise control over or to direct the political or military action of a State” (see Art. 8bis ICC Statute) can commit the crime of aggression. Although it will frequently be the case, it should be noted that the perpetrator need not be a State organ. Second, the “situation” underlying the establishment of the STCoA will have an impact on the personal reach of the STCoA. The Russian Federation and Belarus have committed acts of aggression against Ukraine (U.N. GA Res ES-11/1, paras. 2 and 10). This will be reflected in the nationality of the perpetrators. But again, although it will frequently be the case, the perpetrator need not be a national of the Russian Federation or Belarus.

4.     Territorial Jurisdiction

Statutes of international courts and tribunals usually do not contain a separate provision defining their territorial reach. The territorial jurisdiction of the ICC is a consequence of ratifications of the Statute (Art. 12(2) ICC Statute), ad hocdeclarations accepting the Court’s jurisdiction (Art. 12(3) ICC Statute), and the geographical scope of situations referred to by the U.N. Security Council (Art. 13(b) ICC Statute). In line with the latter, the territorial jurisdiction of ad hoc international tribunals is expressed in their respective mandate. Situations have been limited to the territorial State(s) (Art. 1 ICTY Statute, Art. 1 SCSL Statute) or extended to conduct by nationals of the territorial state (Art. 1 ICTR Statute).

The territorial scope of the crime of aggression is defined by the underlying act of aggression, which necessarily involves cross-border activity. Consequently, the crime of aggression is committed in at least two States, the “aggressor State” (or States) and the “victim State.” So far, two States have committed acts of aggression against Ukraine, the Russian Federation and Belarus (U.N. GA Res ES-11/1, paras. 2 and 10). This could be expressly reflected in describing the competence of the STCoA. However, given that the crime of aggression is still ongoing and further escalation cannot be excluded, it would be advisable to use more open terms such as: “The STCoA shall have the power to prosecute persons responsible for the crime of aggression arising from acts of aggression committed against Ukraine.” Given the cross-border nature of the crime of aggression, this formulation would include conduct committed on the territory of Ukraine as well as conduct committed on the territory of the Russian Federation, Belarus, and any other State that may commit further acts of aggression against Ukraine.

Organization of the tribunal

In order to set up the organizational structure of the STCoA, drafters of a Statute could rely to a large extent on existing statutes of international courts and tribunals. Policy choices may include establishing parallel structures to the ICC in order to create and use as many synergies as possible. Some features of statutes of ad hoc international tribunals on the other hand may have the advantage of allowing for a leaner structure.

1.     Seat

The Hague is proposed as the seat of the STCoA in order to use synergies with other international courts and tribunals, as well as the joint investigation team supported by Eurojust on alleged core international crimes in Ukraine.

A location in The Hague could facilitate smooth coordination and cooperation with the ICC. This is true both for cooperation on the technical level and from the point of view of alleged perpetrators who might face parallel or subsequent trials at the STCoA and the ICC.

2.     Composition

As already discussed, the STCoA will operate within a very limited jurisdictional framework that includes concentration on one situation (aggression against Ukraine), one crime (the crime of aggression) and a limited circle of perpetrators (leadership). This narrowly defined “situation” will allow the tribunal to operate at a relatively small size.

International courts and tribunals usually consist of 3 organs: Chambers, the Prosecutor, and the Registry (Art. 34 ICC Statute, Art. 11 ICTY Statute, Art. 10 ICTR Statute, Art. 11 SCSL Statute). This would also apply to the STCoA. Aligned with the structure of the ICC, though reduced in the number of chambers, the STCoA could consist of one pre-trial chamber of three judges, one trial chamber of three judges, and one appeals chamber of five judges. With a view to financial constraints, one may even think of a further reduction of judges at the pre-trial stage, leaning more toward the practice of a single judge deciding pre-trial matters at the ad hoc criminal tribunals.

3.     Appointment of Highest Judicial Positions and Staff

The selection of the judges, prosecutor, and registrar of the STCoA should be upon the appointment of the Secretary-General of the United Nations. This model would mirror the statutes of other ad hoc criminal tribunals (Arts. 13bis, 16 (with necessary alterations), and 17 ICTY Statute; Arts. 12bis, 15 (with necessary alterations), and 16 ICTR Statute).

An international composition of the organs of the court will best reflect the international nature of a violation of the prohibition of the use of force protected ultima ratio by the crime of aggression. The STCoA will have jurisdiction over individuals, not over States. Still, the definition of aggression is based on the commission of an act of aggression by a State against another State. With the involvement of States as well as high-level state organs in the commission of a crime, the STCoA will be under heightened scrutiny. It is therefore not only imperative to ensure impartiality but to remove any possible doubt of impartiality that might be linked, even if unfounded, to the nationality of a judicial office holder. A truly international composition may help to achieve this goal.

4.     Working Languages

The working languages of the STCoA should be English, French, Russian, and Ukrainian.

English and French are established working languages of international courts and tribunals (Art. 50 ICC Statute, Art. 33 ICTY Statute, Art. 31 ICTR Statute, Art. 24 SCSL Statute for English).

International human rights law guarantees that an accused must be informed promptly and in detail in a language which they understand of the charges against them (Art. 14(3)(a) ICCPR) and to have free assistance of an interpreter if they cannot understand or speak the language used in court (Art. 14(3)(f) ICCPR). These fair trial rights are also reflected in the statutes of international courts and tribunals (Arts. 55, 67 ICC Statute, Arts. 18, 21 ICTY Statute, Arts. 17, 20 ICTR Statute, Art. 17 SCSL Statute) and would form part of the statute of the STCoA. Russian as an additional working language ensures that the language assumingly spoken by a majority of the accused is an integral component of the tribunal’s daily work. It also facilitates outreach to the Russian public, which judging on the current degree of propaganda and disinformation may become a major task for the tribunal. Facilitating outreach to the general public of the victim State suggests using Ukrainian as a working language. It must be ensured that all affected communities have unrestricted access to the work of the STCoA in a language they understand.


In sum, a framework exists to achieve justice for the crime of aggression against Ukraine. That framework must be based on an appreciation of the political and legal context of the present situation and can draw from the practice of international criminal tribunals to date. A clear legal path is available if U.N. Member States can seize the momentum to take it.

IMAGE: Russia’s Foreign Minister Sergei Lavrov (L) speaks at a Security Council meeting on the Russian invasion of Ukraine as US Secretary of State Antony Blinken (R) listens at the United Nations on September 22, 2022 in New York. (Photo by Bryan R. Smith / AFP) (Photo by BRYAN R. SMITH/AFP via Getty Images)