Accountability for the Crime of Aggression against Ukraine

Two years have passed since Russia launched its full-scale invasion of Ukraine – an act of aggression which 141 states of the UN General Assembly (UNGA) condemned as such shortly after. Ever since, calls for accountability of those responsible for this aggression have not stopped. Rightly so, as the crime of aggression is, by definition, a leadership crime that captures the essence of the injustice of a war that has brought unimaginable suffering to the people of Ukraine. The question of how to prosecute the crime of aggression is the subject of an ongoing discussion, with a focus on the establishment of a Special Tribunal for Ukraine during the first year after the invasion.

In the last year, the voices calling for a simultaneous reform of the Rome Statute of the International Criminal Court (ICC) concerning the crime of aggression have grown louder. Indeed, as this blog will highlight in the following, such a reform is necessary and long overdue. The current jurisdictional regime leaves accountability gaps, which have become painfully visible in the past two years. A review of this jurisdictional regime introduced by the so-called Kampala Amendments is scheduled for seven years after its activation in 2018 (Resolution RC/Res.6(4)) and is thus going to take place in 2025. Plausible suggestions for the reform are already out there – it ultimately “all depends on the political will” of the 124 ICC state parties. Germany and other European states, as well as Costa Rica and Vanuatu have already voiced their support for an amendment. Advocating for reform during this review would not only be in the interest of holding the perpetrators of the crime of aggression against Ukraine accountable but could also significantly contribute to overcoming double standards in the international justice system and protect states better against aggression by others. What is now called for is an alliance between states from the Global South and Global North, which support the indiscriminate prosecution of the crime of aggression to take concerted steps towards amending the ICC’s jurisdiction. Germany should live up to its announcements to support this reform process, and it should do so now.

The Urgent Need for Reform of the Rome Statute’s Jurisdictional Regime

In 2010, the Kampala Amendments to the ICC’s Rome Statute introduced a definition of the crime of aggression in Art. 8bis(1) as “planning, preparation, initiation or execution by a person in a position effectively to exercise control over or to direct the political or military action of a state, of an act of aggression which, by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations.” At the same time, an agreement on the ICC’s jurisdiction over the crime was codified in Art. 15bis. Both Articles were activated in 2018. The Kampala Amendments were commended as a huge success after decades of ferocious negotiations of proponents on the need to enforce accountability for the gravest breaches of the prohibition of the use of force as a ius cogens norm.

It was clear from the outset, however, that this political compromise came with a price: besides the high material threshold of a manifest violation of Art. 2(4) UN Charter, it particularly affected the jurisdictional regime, which has been the subject of much critique subsequently (Claus Kreß/Stephan Hobe/Angelika Nußberger, Jennifer Trahan and Astrid Reisinger Coracini, to name a few). Art. 15bis of the Rome Statute deviates from the usual jurisdiction codified in Art. 12 Rome Statute concerning state referrals or proprio motu investigations (in detail Carrie McDougall, pp. 258-352). While it is usually sufficient that either the state whose nationals committed the crime or the state on whose territory it was committed is a state party or accepts the ICC’s jurisdiction ad hoc, Art. 15bis establishes a higher threshold in two respects:

• 15bis(4) foresees an opt-out-clause for state parties. The Article’s precise content remains disputed, but according to the majority interpretation, if the aggressor state has not previously opted out, ratification of the Kampala Amendments by either aggressor or victim state suffices. As an alternative, narrower interpretation, a few states have advocated that both aggressor and victim state must have ratified the amendments for them to apply – a reading which was also negotiated into the 2017 activating resolution, ICC-ASP/16/Res.5. This understanding has been disputed by many states afterwards, and it thus remains questionable if it amounts to a subsequent agreement in the sense of Art. 31(3) of the Vienna Convention on the Law of Treaties, departing from the wording of Art. 15bis(4) (see Jennifer Trahan and Global Institute for the Prevention of Aggression (GIPA)). So far, 45 states have ratified the Kampala amendments, including Germany, but excluding France and the UK – two of the proponents of the narrow reading.
• According to Art. 15bis(5), the ICC’s jurisdiction does not cover crimes of aggression committed by nationals or on the territory of non-member states unless the UN Security Council (UNSC) refers the case to the court (Art. 15ter, Art. 13(b) Rome Statute). Hence, this exception creates accountability gaps in cases of deadlock at the UNSC.

These lacunae in jurisdiction are owing to the opposition of some powerful states to the alignment during the Kampala negotiations – including France, the UK and the US, which, as permanent members of the UNSC, ensured their veto power against the prosecution of non-state party nationals. By contrast, particularly the 33 African Rome Statute member states were very outspoken about their position that “the crime of aggression ought to be treated in the same way as all the other crimes”. Similarly, most South American states and many European states supported the court’s competence for all core crimes. The Non-Aligned Movement also pointed out that the ICC should be able to exercise its jurisdiction independent of the UNSC. The fact that the Kampala Amendments have only been ratified by 45 states – excluding most African state parties – has been partly attributed to the frustration with the restrictive jurisdictional regime as it stands, which cannot deter non-member states.

The consequences of these shortcomings in the case of Ukraine are widely known: While Ukraine has not ratified the Rome Statute despite repeated calls by Ukrainian civil society, it has issued ad hoc acceptances of the ICC’s jurisdiction. Nonetheless, the court remains incompetent to prosecute the crime. While Ukraine and other states that recognize universal jurisdiction over the crime of aggression have opened investigations into Russia’s aggressive warfare (besides Ukraine, e.g. also Lithuania and Poland), they cannot prosecute the troika – the Head of State, Head of Government or Foreign Minister, who enjoy absolute personal immunity before domestic courts. This leaves a glaring accountability gap, considering that the crime of aggression not only violates the prohibition of the use of force – and thus state sovereignty – but leads to grave violations of the human rights of civilians and combatants alike, which war crimes and crimes against humanity can only partially cover.

Accordingly, the establishment of a Special Tribunal for Ukraine has been at the center of international attention. An International Center for the Prosecution of the Crime of Aggression has been set up to gather evidence in the meantime. However, this approach has been criticized because it only covers this exclusive case and, therefore, potentially adds to already existing double standards in the prosecution of international crimes (see already Andreas Schüller). Besides this signal of “selective justice” (see the UN Commission of Inquiry on Ukraine, para 940), concern has been voiced that this further fragmentation of international criminal justice institutions could be weakening the ICC as the international criminal tribunal with universal aspirations.

The Necessary Steps towards Reform

It is against this background that the idea to take a two-pronged approach, supporting a reform of the Rome Statute as a mid- or long-term goal in addition to the establishment of a Special Tribunal, has gained traction. Already during the Assembly of State Parties (ASP) in 2022, Prosecutor Karim Khan called for addressing the accountability gap. Similarly, numerous international legal scholars (e.g. the Nuremberg Academy, Jennifer Trahan, Claus Kreß/Stephan Hobe/Angelika Nußberger), parliamentarians, and civil society organizations are committed to using the international momentum.

Various suggestions for what the reform could look like have been made. In summary, a light version proposed is to enable the UNGA to make referrals to the ICC based on the Uniting for Peace resolution (see Shane Darcey). However, the viability of this approach has been questioned since the UNGA is not competent to take coercive or enforcement actions – not even under Uniting for Peace (see Carrie McDougall). The preferable solution would be a comprehensible alignment of the jurisdictional framework with the other three core crimes, rendering the court competent through ratification or ad hoc acceptance by either the state of nationality of the perpetrators or the state on whose territory the crime of aggression was committed. The Global Institute for the Prevention of Aggression (GIPA), a group of around 50 experts on international criminal law and the crime of aggression with Benjamin Ferencz as former president, has prepared a comprehensive proposal of amendments to achieve this harmonization and an accompanying explanation which could be taken as a basis for discussion of member states.

Admittedly, a certain degree of uncertainty remains concerning the proceedings for such a reform. The necessary first step would be the adoption of an amendment, which under Art. 121(3) Rome Statute requires a 2/3 majority (currently 83 states). What warrants further assessment is the second step since Art. 121(4) and (5) foresee two different regimes for the entry into force of such an amendment. Which one of the two – if any – is applicable to amending the Kampala Amendment, is disputed:

• Some argue that it would enter into force for all state parties one year after ratification by 7/8 of them according to Art. 121(4) (e.g. Kai Ambos and Carrie McDougall, p. 213). This would call for support by 109 states.
• It has also been proposed that amending an amendment constitutes a case not covered by the Rome Statute, thus implying that the quorum of Art. 121(4) is to be determined vis-à-vis the states which have ratified the Kampala Amendment. The modifications would hence enter into force for all of these ratifying parties once 7/8 of the 45 states have agreed to them (see Fiona Abken/Paulina Rob).
• Others argue that the same special procedure, as applied to the Kampala Amendments themselves, should apply based on Art. 121(5) S. 1 in conjunction with the sui generis regime of Art. 15bis. The amendment would thereby enter into force for individual states accepting it one year after ratification (see the GIPA Proposal and Fiona Abken/Paulina Rob).
• It has also been proposed for states to agree to an alternative procedure (GIPA Proposal), such as to have amendments enter into force amongst the states which have ratified the Kampala Amendments immediately after adoption (see the Proposal by Parliamentarians for Global Justice).

As illustrated, despite the open questions around the specific procedure, an amendment towards harmonization of jurisdiction is, in fact, legally possible – it is now solely a question of political will. In fact, a timely opportunity to tackle the lacunae is coming up. The review of the Kampala Amendments is scheduled to take place in 2025. A range of European states, as well as individual Latin American and African states, have already announced their support for reform on the occasion of the 25th anniversary of the Rome Statute in July 2023.

Germany’s Potential Role in the Process

One of the outspoken proponents of the harmonization of the ICC’s jurisdiction is Germany. This does not come as a surprise since Germany was one of the states originally supporting ICC jurisdiction for all core crimes and the sixth member state to ratify the amendment in 2013. In her speech at the Hague Academy of International Law in January 2023, Foreign Minister Annalena Baerbock supported the idea that, besides the establishment of a hybrid Special Tribunal for Ukraine, international criminal justice should be sustainably strengthened by aligning the jurisdiction of the ICC for the crime of aggression. On the German role in the process, she added: “I believe it befits a country such as ours, with our history, to drive this debate forward now.” Since then, the Foreign Minister has repeatedly reaffirmed Germany’s commitment to a revision of the Rome Statute. The Foreign Ministry’s State Secretary confirmed in response to a parliamentary question in February 2023 that the German government was in favour of such a reform. During a hearing held in the Foreign Affairs Committee of the German Parliament in the same month, concerning the establishment of a Special Tribunal for Ukraine, several of the experts pointed out the need for a two-pronged approach to strengthen the ICC and evade the impression of selective justice. Similarly, the German Federal Ministry of Justice spoke out in support of the expansion of the jurisdiction of the ICC. During the last ASP in December 2023, the German delegation emphasized its desire to promote harmonization of the jurisdiction of the ICC together with a “group of friends”, including Costa Rica and Vanuatu.

Against this background, is it astounding how few specific steps have come to be known so far. Despite these numerous statements of support by Germany and similar declarations by other European states as well as by Costa Rica during the last ASP’s general debate, a specific proposal was not introduced. The possibility to kick off a substantial discussion amongst all state parties was thus missed (critically concerning the 21st ASP already, see Kai Ambos). A retrospect on the last 25 years of negotiations concerning the crime of aggression justifies the expectation that finding a majority for such an amendment will be difficult, but it is by no means impossible. While African and most Latin American states remained silent about the reform during the 22nd ASP’s general debate, many of them were staunch supporters of harmonization during the Kampala negotiations. The current momentum would indeed provide an opportunity for them to take the lead and introduce a jurisdictional regime which could more effectively deter powerful states from aggressive wars. What is thus called for is an alliance between states from the Global South and Global North, which already supported ICC jurisdiction for all four core crimes during negotiations in Kampala (in this sense also Claus Kreß). States in favour of the reform should immediately act upon their announcements, introduce a specific proposal, and begin to rally for the necessary majorities for the first step, the adoption of an amendment. It is imperative that Germany supports these efforts to the best of its ability. The proposal should be circulated as soon as possible and then tabled openly during the next ASP in December 2024 so states can be called out on contradictions between their positions concerning accountability in the specific case of Ukraine and for the crime of aggression generally. Given that the opportunity of the review scheduled for 2025 is already around the corner, there is absolutely no time left to wait (see similarly Astrid Reisinger Coracini and Jennifer Trahan).

Legal Implications for Ukraine – Retroactivity of an Amendment

The important question which remains is what implications such a reform could still have for seeking accountability concerning the crime of aggression committed against Ukraine. One concern which has been raised is whether an amendment would lead to a retroactive application of the crime of aggression, thereby violating the principle of legality as enshrined in Arts. 22 to 24 Rome Statute. It should, however, be noted that the nullum crimen principle only forbids substantive retroactivity, meaning that the individual must have been able to know due to a prior source of criminal law that their conduct was prohibited (see Talita de Souza Dias, p. 66 f.). The crime of aggression has, however, constituted customary international law for decades and has been “within the jurisdiction of the Court”, Art. 22, at least since 17 July 2018 (see similarly Claus Kreß/Stephan Hobe/Angelika Nußberger). Moreover, the commission of the crime of aggression can be considered ongoing, and Art. 8bis will thus continue to be violated until the acts of aggression, as defined in Art. 8bis(2), cease (see also Astrid Reisinger Coracini; on the notion of execution of an act of aggression Otto Triffterer/Kai Ambos, p. 590). The ICC could, accordingly, exercise a reformed jurisdiction for the crime of aggression in the situation of Ukraine. Ukraine should thus ratify the Rome Statute and participate in the amendment process as the Court’s newest member state.

A Need for the ICC Beyond a Special Tribunal for Ukraine

In the case of the set-up of a Special Tribunal, a revised jurisdictional regime would raise questions on the relationship of both institutions – the Tribunal and the ICC (in detail Kai Ambos). It should, however, be kept in mind that a hybrid tribunal would likely be unable to prosecute the troika due to personal immunity, still leaving the need for the ICC. By contrast, establishing an internationalized Special Tribunal based on a UNGA resolution excluding personal immunity would likely take time as well. But even if a Special Tribunal should already be in place, a reform of the ICC’s jurisdiction is, in any event, crucial for the legitimacy of the entire international justice system and would ultimately have implications for the legitimacy of the judgements rendered by a Special Tribunal. A fundamental pillar of the credibility of international justice is the equal application of the law to all. It is thus imperative to ensure full accountability in the case of Ukraine but not to stop short there. Although it is a grim scenario, the jurisdictional gap will certainly play a role again in the future. As the war of aggression against Ukraine painfully illustrates, we are not talking about an abstract possibility.

Conclusion

One must imminently utilize the momentum for reform of the Rome Statute’s jurisdiction concerning the crime of aggression. Germany should follow up on its commitment to strengthening international criminal justice and support concerted efforts to table a proposal in time to find majorities for the adoption of an amendment during the review of the Kampala Amendments in 2025. Driving the reform process forward and not missing this historic chance is crucial – both for the efforts for accountability in Ukraine and for the credibility of international criminal justice as a whole.