As the conflict in Ukraine is about to enter its second year, Ukraine and the West are accelerating efforts to ensure that Russian President Vladimir Putin doesn’t get away with his illegal war. That has meant the West supplying weapons that were previously off the table, but it has also meant renewed attention to accountability. In November, Ukrainian President Volodymyr Zelensky made clear that justice is a key condition for peace. “This,” he explained, “is what stokes the greatest emotions.” But while there are courts where Russians can be prosecuted for war crimes, crimes against humanity, and genocide, a major piece is missing: there is nowhere to try Putin and other top Russian leaders for launching the war in the first place. For this, a special tribunal for the crime of aggression is needed.

For months, Ukrainian representatives have been quietly working to generate support for a special tribunal. The proposal picked up steam in mid-December, when the president of the European Commission, Ursula von der Leyen, endorsed the creation of a tribunal and pledged to “start working with the international community to get the broadest international support possible for this specialized court.” In mid-December, while accepting the European Union’s top human rights award, Zelensky called on states to form a special tribunal to prosecute “the crime of Russian aggression.” At the same time, a Ukrainian delegation, hoping to capitalize on the momentum, arrived in Washington, D.C., seeking U.S. support for a special tribunal.

The effort to establish a special tribunal may seem quixotic. After all, plenty of criminal investigations into crimes committed by Russians during the war are already underway in both domestic and international courts. Why add another court to the mix? But without a special tribunal for the crime of aggression, the fundamental crime of launching and waging this illegal war—a crime without which the other crimes would not have taken place—would go entirely unpunished. Creating a court that has jurisdiction to try this crime is an essential step in the global effort to reject Russia’s blatantly illegal war and, with it, Putin’s willingness to destroy the modern international legal order in pursuit of a new Russian empire.


When legal scholars speak of the crime of aggression, they mean the crime of waging an illegal war. Since the end of World War II, that has meant a war that violates the UN Charter, which prohibits states from using force against any other state unless they are acting in self-defense or have been authorized to use force by the UN Security Council. For much of history, however, there was no such thing as a crime of aggression, because aggressive wars were perfectly legal. Indeed, military conflict was an accepted method of settling international disputes. States could go to war for any number of reasons, including to collect debts, to enforce treaties, and to protect trade routes. That changed only in 1928, when nearly every country in the world joined the Kellogg-Briand Pact, which for the first time outlawed war, prohibiting states from using war “as an instrument of national policy.”

The first court with jurisdiction to try this new crime was the International Military Tribunal established at Nuremberg, Germany, after World War II. There, 24 Nazi leaders faced trial for crimes committed during the war, including the “crime against peace,” as it was then called. Prosecutors—including Robert Jackson, who took a leave of absence from his position as a U.S. Supreme Court justice to serve as a prosecutor in Nuremberg—filed an indictment, the first count of which charged defendants with participating in a conspiracy to commit acts of aggression, noting that the “invasions had been specifically planned in advance, in violation of the terms of the Kellogg-Briand Pact of 1928.” The second count charged defendants who “participated in the planning, preparation, initiation, and waging of wars of aggression.” (Similar charges were made in the International Military Tribunal for the Far East in Tokyo, which tried Japanese leaders for starting and waging war.)

The Nuremberg court found eight defendants guilty of the first count and 12 guilty of the second. In its judgment, it explained the foundational importance of the crime: “To initiate a war of aggression . . . is not only an international crime; it is the supreme international crime differing only from other war crimes in that it contains within itself the accumulated evil of the whole.”

The only other international court with jurisdiction over the crime of aggression is the International Criminal Court (ICC), created in 2002. The treaty that established the court, the Rome Statute, granted the court jurisdiction over the crime of aggression. But the crime could not be prosecuted until a conference of the states that had ratified the treaty could agree on the definition of the crime. That task was only completed in 2010, when the conference of states parties met in Kampala, Uganda, to amend the statute to fill in the missing pieces. The drafters limited criminal liability to “manifest” violations of the UN Charter by any person engaged in “planning, preparation, initiation or execution” who was “in a position effectively to exercise control over or to direct the political or military action of a State.” This meant that only those most responsible for the war, and not ordinary soldiers, could be prosecuted (though only after the amendments became effective, in 2018). In a concession to the United States, which participated as an observer, the conference also agreed to limit the exercise of the court’s jurisdiction over the crime to wars of aggression committed by states that had ratified the Rome Statute as well as the new amendments. The United States signed but never ratified the treaty; thus, no citizen of the United States can be charged for the crime of aggression in the ICC.


No citizen of Russia can be charged for the crime of aggression, either. Like the United States, Russia signed but never ratified the Rome Statute. Belarus, too, never ratified the treaty, and it therefore cannot be held to account by the court for its complicity in the illegal war, including by allowing Belarusian territory to be used in service of Russia’s war.

Although the ICC does not have the power to prosecute the crime of aggression committed by Russian or Belarusian citizens, the ICC does have the power to prosecute war crimes, crimes against humanity, and genocide in Ukraine. That’s because countries gave the court broader jurisdiction over these crimes, allowing it to prosecute the nationals of nonmember states if the crime is alleged to have been committed on the territory of a state that has agreed to the jurisdiction of the court. This is why the United States could be investigated by the court for alleged crimes, including torture, committed by its forces in Afghanistan. While the United States is not a party to the Rome Statute, Afghanistan is, meaning that crimes committed on its soil can be investigated by the court. In Ukraine, the court has had this same authority since 2014, when Ukraine first submitted to the jurisdiction of the court. (It extended that submission indefinitely in 2015.) Indeed, Karim Khan, the chief prosecutor of the ICC, has opened investigations into those atrocity crimes. Khan himself has traveled to Ukraine several times, including an April visit to the town of Bucha, where he saw mass graves and listened to survivors’ accounts of the Russian occupation.

But Khan is unable to lead the way on the crime of aggression in Ukraine because of the restrictions placed on the ICC in Kampala. This is a difficult truth for Khan. In December, at an annual gathering of the states that are party to the Rome Statute in The Hague, he tried to throw cold water on the proposal to create a special tribunal to try the crime of aggression. “The EU has misstated the law,” he declared, in an apparent effort to push back against von der Leyen’s statement the week before in support of a special tribunal. “We should avoid fragmentation, and instead work on consolidation,” he urged.

Khan’s statement, which was made the day before the Ukrainian delegation met with members of the U.S. House of Representatives and Senate, took some of the air out of the campaign to create a court. It left some U.S. policymakers thinking that if the most public face of the international criminal investigations in Ukraine opposes a tribunal, then maybe it isn’t such a good idea after all.

But Khan’s position may be motivated more by a desire to keep the limelight on himself than by principled objection. He is likely also concerned that more funding for a special tribunal will mean less funding for the ICC, which is chronically underfunded as it is. Unfortunately, “consolidating” these charges—bringing them all under the ICC’s umbrella—is not an option, at least not for the war in Ukraine. Although the war has renewed interest in amending the Rome Statute so that the crime of aggression can also be prosecuted against states that commit the crimes on the territory of a state that has accepted the court’s jurisdiction (as is true for the other crimes), such an amendment would likely take years to enact. The best way forward is therefore a two-track approach: a special tribunal for the crimes of aggression in Ukraine and an amendment to the Rome Statute to expand the court’s jurisdiction so that a special court will not be necessary in the future.


Despite Khan’s objections, support for the idea of a special tribunal to try the crime of aggression is growing. But how it should be done remains an open debate.

The first widely circulated proposal, put forward by former British Prime Minister Gordon Brown and several other heads of state and legal experts, called for a special tribunal modeled on Nuremberg. But that approach has drawn criticism; some argue that a tribunal created by a few Western states would not have the legitimacy of one created under the auspices of an international organization. And what would stop, say, Russia, Belarus, and Syria from creating a competing “international court” of their own?

Alternative plans have emerged one after another. There was a proposal to establish a hybrid tribunal under the auspices of the Council of Europe that would be called the Extraordinary Ukrainian Chamber for Aggression. But the proposal would have required unanimity among members of the Council of Europe, and it never picked up steam. What about simply leaving it to the Ukrainian courts? Ukrainian domestic law, after all, criminalizes “planning, preparation and waging of an aggressive war.” But domestic courts are obligated to recognize the immunity of foreign heads of state, heads of government, and the foreign minister, which would mean that Putin and his foreign minister, Sergey Lavrov, would be out of the Ukrainian courts’ reach. (The same would likely be true of the proposed hybrid tribunal.) Russian generals could not take advantage of personal immunity, which applies only to those at the very highest level of government, but they would likely seek to claim functional immunity if prosecuted in Ukrainian courts, arguing that they cannot be held criminally responsible in a foreign domestic court for performing official acts. Those same immunities would not apply in an international court acting on behalf of the international community.

The proposal with the most widespread support at present (and the one I have advocated) is a court created through the UN. This would require agreement between Ukraine and the UN, after a vote of the General Assembly recommending its creation. This would be fitting: after all, the court would be created precisely to enforce and reaffirm the UN Charter’s prohibition on the use of force. And creating the court through a vote in the General Assembly would give every country in the world a chance to reject Putin’s illegal war and endow the special tribunal with powerful international legitimacy.

For much of history, aggressive wars were perfectly legal.

But there are drawbacks. While over 140 members of the General Assembly voted for both resolutions condemning the war, it is far from clear that a resolution to create a court would garner nearly as much support. Some worry that African states, in particular, would object. Although only four countries joined Russia in voting against the earlier resolutions, there were many more abstentions, a large proportion from African states, some of which are reliant on trade with Russia and others of which are simply uninterested in getting in the middle of what they see as a great-power conflict. Others share Khan’s concern that funding for a special court would mean that the ICC’s ongoing cases in African states would continue to be starved for resources.

Scholars and diplomats have pointed out the double standard they see in calls to create a special court to try the crime of aggression by Russia when no mention has been made of holding U.S. or British leaders to account for the 2003 invasion of Iraq, which violated the UN Charter by launching a war without clear Security Council authorization. (The United States argued that the Security Council had authorized military intervention when it gave Iraq “a final opportunity to comply with its disarmament obligations,” but few agreed. ) That war set off a cascade of cataclysmic events and contributed to the rise of the Islamic State (or ISIS) and the Syrian refugee crisis.

Yet failure in the past need not dictate failure in the future. All states have a great deal at stake in the Ukraine conflict. The war has disrupted grain exports from Ukraine, raising food and fuel prices around the world and contributing to placing 49 million people in 49 countries on the edge of famine. And it has upended energy markets around the globe. All states benefit from an effective global prohibition on wars of aggression and territorial conquest. A court created exclusively by European states, rather than through the UN, risks sending the message that the crime of aggression will be enforced only in Europe. The message should instead be that the entire world has been wronged by this war, and the entire world deserves to play a role in punishing the crimes committed in the initiation, planning, and prosecution of it.

The Biden administration has thus far been silent on the proposal to create a special tribunal. Ambassador-at-Large for Global Criminal Justice Beth Van Schaack attended the ICC convention in The Hague in December and has repeatedly voiced support for that court, a welcome reversal of the position taken by the Trump administration, which placed economic sanctions, usually reserved for international law offenders, on the court’s personnel. Given concerns about double standards, the United States can probably help the case for a special tribunal most by quietly supporting the effort but letting others take the lead. In the meantime, it could assist in evidence collection and preservation of all four Rome Statute crimes—an overwhelming task important to both the ICC and a future special tribunal.


The fight to establish the special tribunal centers on not how the war is waged but that the war is waged at all. This is why simply prosecuting the crimes already before the ICC is not enough. A war crime is a serious violation of the rules that regulate the conduct of belligerents during a war, commonly referred to as the law of armed conflict. For example, the law of armed conflict requires that belligerent states target only objects with a military purpose, not civilians or civilian objects. It is not a war crime for Russian soldiers to kill Ukrainian soldiers in combat. It is not a war crime for Russian missiles to destroy a Ukrainian military base. It is not a war crime for Russia to try (and try and try) to kill Zelensky. And while civilians cannot be targeted, it is not a war crime to kill them as long as their deaths are proportionate to the military purpose—then, they are mere (legal) collateral damage. Yet all this death and destruction is a direct result of Russia’s decision to launch an illegal war of aggression against Ukraine.

Even if the Russian leaders can be directly connected to individual war crimes, crimes of humanity, or acts of genocide and therefore be prosecuted by the ICC—far from certain, given the high evidentiary standards that must be met to connect them to particular events on the ground—prosecuting them only for these crimes would let the Russian and Belarusian leadership off the hook for many of the worst injustices that they have committed in this war. It would leave the Ukrainian soldiers who have died in combat, the vast majority of whom were civilians before the war, without justice. It would leave the Russian soldiers, many of them plucked from impoverished ethnic minority communities and sent to their deaths with little gear or training, without justice. It would leave those who have lost their homes and had to flee for their lives without justice. And it would leave civilians who were not directly targeted but who were “collateral damage” in Russia’s pursuit of targets with military purpose without justice.

Putin has no legal basis to wage this war, and the justifications that he points to are meritless. When he launched what he insisted on calling a “special military operation,” he made a variety of claims, including outrageous (and baseless) assertions of genocide by Ukraine. In a speech made on the eve of the war, Putin made equally baseless claims that he was acting in individual self-defense of Russia and collective self-defense of parts of eastern Ukraine that Russia had recognized as independent and with which it had concluded mutual military assistance “treaties.”

Support for the idea of a special tribunal to try the crime of aggression is growing.

Zelensky and his team understood that to win the public support at home and abroad that Ukraine needs to win the war, they had to make clear that these claims were false. They needed to show that the war was not just an assault on Ukraine but also an assault on every country’s right to sovereignty. On the day the war began, Zelensky declared, “If you, dear European leaders, dear world leaders, leaders of the free world, do not help us today, then tomorrow the war will knock on your door.” Ukraine has survived longer than anyone predicted by rallying the world behind the vision that Ukraine is not fighting only for its own survival but for the survival of the rules-based international order.

The war in Ukraine began as the greatest threat to the international legal order, but it may turn out to be its salvation. When Russia, a veto-wielding permanent member of the UN Security Council possessing the largest nuclear arsenal in the world, invaded Ukraine in a blatant violation of the UN Charter, many began writing the obituary of the international legal order. Pundits mused that China’s invasion of Taiwan might be next.

Ukraine responded by waking dormant institutions of international law and, in the process, reviving global resolve to enforce the prohibition on war. Again and again, states have stood up to denounce the Russian invasion and the assault on the legal order that it represents. Now the task is to create a genuinely international judicial institution with the power to label Putin’s war not just wrong but also criminal. Only once that is built can the world provide justice to all those who have died and suffered in the war—and reaffirm the prohibition against war as an inviolable rule of the international order.

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  • OONA A. HATHAWAY is Gerard C. and Bernice Latrobe Smith Professor of International Law at Yale Law School.
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