Ukraine and the promise and peril of lawfare

Three years of war in Ukraine invite solemn reflection on how the war has been conducted and how both countries have conducted themselves in international fora. Given Russia’s pretext for the war—a spurious allegation that Ukraine was committing genocide against ethnic Russians and Russian speakers in its eastern territories—it isn’t surprising that the war has been fought on the battlefield and in international institutions, especially courts.

Upon the outbreak of war, Ukraine quickly sought recourse from the International Court of Justice (ICJ) and the International Criminal Court (ICC), among other international institutions. This was an intuitive choice: international law prohibits territorial aggression, the wilful killing of civilians, and the wanton destruction of the infrastructure that people rely on to live. Kyiv, alleging these and other abuses, hoped the international bodies would provide legal remedies and diplomatic and economic support for the cause of sovereignty, democracy, and human rights in Ukraine.

But has Ukraine succeeded in its “lawfare” with Russia? It may take years to draw conclusions. However, the Ukrainian government’s legal mobilization at multiple international fora reveals both the promise and peril of lawfare.

In court, legal arguments are more important than moral ones

On February 26, 2022, just two days after Russia began its full-scale invasion, Kyiv sought legal recourse at the ICJ, one of the six principal organs of the United Nations, which adjudicates legal disputes between states. Fifteen elected judges comprise the court’s bench, each serving nine-year terms. In contrast to other U.N. bodies, such as the Security Council and the General Assembly, the ICJ is intended to be less political. The judges don’t represent any one country, and they work toward consensus as they rule on questions of international law (though they don’t always reach a consensus).

The ICJ is the main international body charged with determining violations of the 1948 Genocide Convention, so Ukraine turned to this court first. In its complaint, Kyiv argued that Moscow’s false claim of genocide, which it used as a pretext for the war, constitutes a violation of the treaty, which both Ukraine and Russia (then the Soviet Union) ratified in 1954. Essentially, according to Ukraine, Russia was distorting the responsibility to protect principle to justify its naked territorial aggression. Ukraine therefore asked the court to rule that it wasn’t committing genocide against ethnic Russians and Russian speakers and, as a consequence, Russia had to halt its military operation.

There was great promise in Ukraine’s novel legal argument: if there was no legal basis for the war, the war was illegal, and the court could rule that it must end.

A few weeks into the war, ICJ judges said they hadn’t seen evidence to corroborate Russia’s genocide claim but, two years later in February 2024, they ultimately decided not to rule on Ukraine’s core contention, that Russia lacked a legal basis for the war. The judges were persuaded by Russia’s argument that the ICJ lacked jurisdiction: the 1948 convention doesn’t address the potential issue of false genocide accusations nor armed interventions based on such accusations.

This case shows that misusing international law may be immoral, but it isn’t necessarily illegal. A peril of lawfare is that the law—not just morality—must be on your side. The law wasn’t on Ukraine’s side this time.

To add to the case’s painful irony, the ICJ now has to rule on Ukraine’s second contention, that it hasn’t committed genocide—an issue that Kyiv, not Moscow, asked the court to adjudicate. Ukraine’s case against Russia has become a case about just Ukraine.

Ukraine has filed other complaints against Russia at the ICJ over the past decade, which it hasn’t technically lost or outright won; ICJ judges have found insufficient evidence for many of Kyiv’s arguments. This isn’t to say that Kyiv has brought frivolous suits against Moscow; to be sure, a major challenge with lawfare is that it’s based in conflict zones, where it’s often difficult to gather systematic evidence of international law violations.

Fortunately for Kyiv, adverse judgments at the ICJ don’t seem to have undermined international solidarity with Ukraine. 

International court decisions don’t always result in compliance 

When they initiated complaints against the Kremlin, Ukrainian leaders surely knew that even if the international judges were to rule against Russia, Moscow’s compliance with the decisions couldn’t be guaranteed. For example, while ICJ judges were reviewing Ukraine’s genocide complaint, they ordered several interim measures, including that Russia halt its military operation and ensure Russian-backed paramilitary groups or “irregular units” suspend their activities. The judges also enjoined both Russia and Ukraine not to escalate the conflict.

The Kremlin said that the court’s decision was invalid because Russia hadn’t consented to the proceedings. However, as a party to the Genocide Convention, Russia has consented to the ICJ’s jurisdiction over disputes related to the treaty.

In any case, it was evident that Moscow wouldn’t—and ultimately didn’t—comply with the ICJ’s initial ruling. A larger, related problem is that enforcement of ICJ decisions resides primarily with the U.N. Security Council, where Russia has used its veto power to block resolutions calling for an end to the war.

International rules should apply to all countries

Ukraine became the ICC’s 125th member on January 1, 2025, after ratifying the Rome Statute in late 2024. (Russia isn’t a member.) Ukraine was praised for ratifying the treaty but was also criticized for adding a surprising condition to its ICC membership.

Ordinarily, international courts don’t have jurisdiction unless both parties consent. But the Rome Statute grants jurisdiction to the ICC over acts committed on the territory of a member state or a state that has accepted ICC jurisdiction via an Article 12 declaration. This includes acts committed by nonmember nationals. (This is essentially a workaround for the consent principle.)

Kyiv filed an Article 12 declaration in 2015, granting the ICC jurisdiction over “acts committed in the territory of Ukraine since 20 February 2014” for an “indefinite duration.” This is how Russians became exposed to ICC scrutiny. But when Kyiv finally ratified the Rome Statute, it invoked Article 124, a rarely-used flexibility provision in the treaty, declaring that it wouldn’t accept the ICC’s jurisdiction over possible war crimes committed by Ukrainians for seven years. In so doing, Kyiv seemed to revoke its previous Article 12 declaration.

This move came out of left field: Kyiv’s Article 12 declaration has provided the entire basis for the ICC’s investigation into the Russia-Ukraine war and its jurisdiction over Russians in Ukraine, despite Russians being nonmember nationals. Ukraine’s move is incongruous with its prior public presentations as a country that adheres to international law, and raises suspicions that Kyiv wants international law to only apply to its adversaries.

There are a number of ways to interpret the legal effect of an Article 124 declaration, as law professor Tom Dannenbaum has discussed in detail, including that, for a limited period: a country doesn’t accept the ICC’s jurisdiction over (1) war crimes committed by its nationals or (2) war crimes committed on its territory (by its nationals or by foreign nationals).

Under the first scenario, the ICC could no longer exercise jurisdiction over Ukrainians but could still exercise jurisdiction over Russians in Ukraine. (The ICC also wouldn’t be able to exercise jurisdiction over Ukrainians in Russia.) But it’s unlikely that the court would interpret the Rome Statute in this way; the ICC has historically rejected states’ attempts to restrict investigations to one side of a conflict.

Under the second scenario, the ICC could no longer exercise jurisdiction over Russians and Ukrainians on Ukrainian territory. This would in effect give both sides a “free pass”—something that is at cross purposes with the international rule of law. Per Dannenbaum, this would be a “spectacular own goal” on Ukraine’s part, running counter to its otherwise commendable legal mobilizations against Russia. (Already, the ICC has issued warrants for the arrest of Russian President Vladimir Putin and three senior Russian officials for war crimes and crimes against humanity, with others possibly in process.)

In a third scenario, the ICC could decide that it retains its original jurisdiction over Rome Statute crimes committed on Ukrainian territory by Ukrainian or foreign nationals from February 2014 onward, but that it can only exercise jurisdiction over possible war crimes by Ukrainians on foreign territory (i.e., Russia) from January 2032 onward. This is the least problematic scenario, but it is problematic nonetheless.

If Ukraine wants Russia to be bound by international rules prohibiting war crimes, Ukraine must also be bound by these same rules.

Ukrainian military and security officials are rightfully concerned about possible ICC scrutiny, as should officials in all member countries. While much focus is placed on the ICC’s power to shame and punish offenders, it also has an important responsibility to help deter serious crimes.

If Ukraine doesn’t withdraw its Article 124 declaration, it opens itself up to accusations of double standards and hypocrisy on the world stage and undermines the ICC and international actors and institutions committed to accountability for perpetrators and justice for victims—in this conflict and in countless others around the world.

International law ambitiously strives to constrain state behavior in the international system—that’s its promise. But the way the system is structured allows, and even tempts, some to not comply—that’s the peril. It therefore becomes the responsibility of third parties to create political conditions that make compliance preferable to noncompliance. Thus far, this has fallen short in Ukraine, leaving Kyiv to fight a war initiated under false pretenses, both on the battlefield and in the courts.