The ICC at 20 and the Crime of Aggression

By Tom Dannenbaum, Assistant Professor of International Law at the Fletcher School of Law and Diplomacy at Tufts University 

As the International Criminal Court (ICC) enters its third decade, the Court is at an inflection point. So, too, is the criminalization of aggression. However, while the catalyst for these pivotal moments is the same, the trajectories are different. Optimally, that divergence would be narrowed by an amendment to the Rome Statute’s jurisdictional provisions on aggression. Realistically, however, the route forward on aggression is likely to bypass the ICC. Provided that certain conditions are met to address the problem of selectivity, ensure the institution’s moral standing, and bolster the aggression ban, a special international tribunal would be the most promising alternative option. But those conditions may not be attainable. In that scenario, states should support Ukraine’s exercise of territorial jurisdiction over the crime.

The ICC at an Inflection Point

Following the jubilation at Rome (p. 180) and a strikingly quick progression to the Statute’s entry into force, it did not take long for the ICC’s difficulties to mount. In the Court’s first two decades, convictions have been few and controversial, key arrest warrants have gone unfulfilled and widely ignored, high-profile cases have collapsed, investigations appear to have been undermined, cooperation has been withheld, neocolonial bias has been alleged, states have withdrawn or threatened to, and the world’s most powerful state has brazenly attacked the institution (with the Court initially cowering in response). When the third chief prosecutor, Karim Khan, began his term in June 2021, the Court was in a seemingly intractable malaise. Among the predicaments were two completed preliminary examinations held in indefinite suspension, not because Khan’s predecessor Fatou Bensouda had deemed investigations unwarranted, but because proceeding would strain an overextended institution.

One of those situations (p. 68) involved alleged war crimes and crimes against humanity in Ukraine, where there was an armed conflict in Donetsk and Luhansk, and a belligerent Russian occupation of Crimea. The suspension did not last long.

On 24 February 2022, Russia escalated its aggression into a full-scale invasion. Almost immediately, the new Prosecutor announced his intention to request Pre-Trial Chamber authorization to open an investigation, noting that a State Party referral would obviate that procedure. Within days, he received an initial 39 (later 43) referrals— a show of support without precedent in ICC history. Soon, States Parties began to make ad hoc contributions, again at unprecedented levels. Even the United States, having only recently walked back sanctions on Bensouda and her colleague Phakiso Mochochoko, was prompted to adopt an openly supportive posture. This is anything but a moment for triumphalism and there is much to critique. Nonetheless, with Khan prominent in investigating war crimes, crimes against humanity, and possibly genocide in Ukraine, a renewed sense of institutional purpose is palpable.

The Crime of Aggression and the ICC

And yet, there is a gap. The crime of aggression—the crime without which none of the others would be occurring — is beyond the ICC’s reach. This is not due to a drafting oversight. Powerful states, including those now calling for Russian leaders’ accountability, insisted on a crime-specific jurisdictional straitjacket precisely so that the Court would be unable to sit in judgment of an aggressive war perpetrated by a permanent member of the Security Council. The point was to create the incapacity that now precludes ICC scrutiny of Russia’s resort to war.

Aggression has long been a fraught issue at the ICC. In the 1990s, a significant number of states, particularly from the Non-Aligned Group, insisted on its inclusion in the Rome Statute, while a minority, including the United States, resisted. The ensuing compromise was an amorphous recognition of aggression’s criminality — a placeholder without definition or effect.

It did not take long for the gap to matter. Nine months after the Statute entered into force, the United States and United Kingdom led what a British Foreign Office lawyer characterized as a criminally aggressive war against Iraq. The general limits on ICC jurisdiction allowed only an examination of alleged war crimes by UK troops — crimes that successive prosecutors declined to investigate, first due to insufficient gravity and later with reference to complementarity. However, the emptiness of the Statute’s nod to the criminality of aggression underpinned a more glaring omission.

Battles over the place of aggression continued, first in negotiations regarding an amendment incorporating the crime (agreed in Kampala in 2010) and then in negotiations over whether to activate it (agreed in New York in 2017; effective in 2018). At each stage, progress was precarious and concessions were extracted. The result was a crime that (absent Security Council referral) can come before the ICC only when both states in the relevant dyad have ratified both the ICC Statute and the aggression amendments.

Despite that jurisdictional deficiency, the Kampala and New York agreements included vital achievements. Failure at either stage would have cast doubt on the enduring criminality of aggression after half a century of dormancy. Consensus support among ICC States Parties instead reaffirmed the crime’s customary status. Meanwhile, codified elements introduced specificity. These hard-won gains affirmed aggression’s justiciability, bolstered domestic and regional codification, and contributed to the recognition of aggression as a massive human rights violation.

Nonetheless, just as the invasion of Iraq in 2003 exposed immediately the implications of the placeholder reference to aggression in the original Statute, so Russia’s aggression against Ukraine has spotlighted the moral bankruptcy of the post-2018 jurisdictional framework.

Paths Forward

Here, too, there is an inflection point. Ukraine and other states have initiated domestic investigations of aggression. Separately, creative efforts to establish one or another form of special international tribunal for prosecuting the crime are underway.

Ukraine’s preference appears to be for an international tribunal evocative of Nuremberg. Amending the ICC Statute to allow for General Assembly referrals (Haque) would offer that weight, while ensuring a framework for future cases. It would be the optimal path. However, the very politics that created the existing ICC framework are highly likely to maintain it — an amendment would require support from seven-eighths of States Parties (art. 121(6)). Alternatively, a special tribunal underpinned by broad (ideally General Assembly) endorsement and combined with an effective campaign for Kampala amendment ratification and domestic codification could function in the current case and invigorate efforts to strengthen the ban. Like the ICC, such a tribunal could credibly obviate status immunities.

If such efforts fail, domestic avenues will be pursued. Ukrainian courts have already issued aggression convictions in two cases arising prior to the 2022 escalation, albeit with limited transnational resonance due to one involving an in absentia trial and the other omitting the leadership element of the crime. As further investigations advance, third states should support Ukraine’s domestic pursuit of well-founded aggression cases with investigative assistance, the transfer of evidence, the recognition of lawful arrest warrants, expressive endorsement, and otherwise.

Doing so would emphasize the grounding of Ukraine’s response in international law and rebuff attempts to characterize it as victor’s justice (on that concern, see here). Indeed, the response of third states can play a key role both in checking the pretextual abuse of international criminal law by domestic institutions and in boosting the appropriate exercise of that authority, which is important for aggression just as it is for any other international crime. The overwhelming majority of states have recognized that Ukraine has the law on its side. The upshot ought to be not only that Ukraine may fight and kill in self-defense, but that it may bring that law to bear on those responsible (in a similar vein: p. 278).

Support for domestic proceedings would also manifest state practice and opinio juris in favor of victim states’ territorial jurisdiction and the non-applicability of functional immunities in aggression cases. On both fronts, skeptics have emphasized aggression’s definitional character as an interstate act (para. 222). However, this is also true of war crimes by state forces in an international armed conflict. Ordinarily, it is understood that when interstate violations are also international crimes, the responsible individuals can and should be held accountable, including in domestic court (para. 241). Support for Ukraine exercising territorial jurisdiction would reject the artificial isolation of aggression in this respect. Status immunities are likely to block arrest warrants for President Vladimir Putin or Foreign Minister Sergey Lavrov for as long as they remain in office. However, that protection will cease when they leave and does not apply even now to others at the leadership level.

Support for Ukraine’s exercise of domestic jurisdiction over the crime of aggression may also spotlight the empowering (and not only constraining) effect of criminalizing aggression on the codifying state. That could stimulate codification efforts. Plainly, criminalizing aggression would not itself prevent the codifying state from resorting to aggressive war (art. 353). However, the clearly codified risk of criminal accountability can shift the dynamics of government decision-making at the margins (pp. 2-3), empowering antiwar voices and potentially provoking higher-level resistance or resignation. The prospect of their own criminal liability can also strengthen leaders of potential coalition partners in resisting the pressure of allies to participate in aggressive wars.

Finally, affirmation of the viability of domestic jurisdiction over the crime could bolster aggression’s justiciability in non-criminal contexts, such as those involving human rights and refugee protection. Recognition of aggression’s legal relevance in those areas is growing, but precedent establishing how domestic institutions should go about evaluating the jus ad bellum is sparse.

Ultimately, if a well-structured international tribunal proves nonviable, it would be a mistake to discard the domestic alternative. International support for Ukraine in that respect would have immediate and long-term benefits.

This piece is republished from Völkerrechtsblog.