International Law and the Russian Invasion of Ukraine

Ingrid (Wuerth) Brunk
Friday, February 25, 2022, 12:07 PM

Now is the time for a narrower, more focused international legal order dedicated to a strong core of sovereignty-protecting norms that preserve the territorial status quo and promote international peace and cooperation.

Row of flags in front of the U.N. General Assembly building in New York. (Yerpo,; CC BY-SA 3.0,

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Now is the time for a narrower, more focused international legal order dedicated to a strong core of sovereignty-protecting norms that preserve the territorial status quo and promote international peace and cooperation.

Russia’s invasion of Ukraine violates Article 2(4) of the U.N. Charter, which prohibits the use of force against the territorial integrity of another state. Russian President Vladimir Putin cloaked Russia’s military action in legal justifications during his speech on Feb. 24. While the justifications were absurd, his speech highlights that international law retains some rhetorical significance while it simultaneously underscores how weak the legal restraints are in practice. An examination of Russia’s legal justifications shows that well-meaning (or apparently well-meaning) actions by the United States (and others) purportedly designed to promote humanitarian and human rights objectives have eroded international legal norms. The point is not to draw moral equivalents nor to justify Russia’s horrific actions against Ukraine. The point is that the international legal rules on territorial integrity are weakening—a dangerous development. In response, the international community should condemn the Russian invasion as a violation of international law in no uncertain terms. But also, the international community should promote a clear-eyed, restrained version of international law designed to generate interstate peace through territorial settlement, one that holds even in an increasingly dangerous world.

Article 2(4) and More: International Legal Rules and Territorial Integrity

Russia points to Kosovo, Iraq, Libya and Syria. Interventions in those countries were justified by the United States and its allies based on humanitarian intervention, expansive claims of individual and self-defense, the protection of human rights, and strained readings of U.N. Security Council resolutions. Russia seems to cite these precedents to show how the West itself has undermined the prohibition on the use of force in international law. The clearest legal justification for Russia’s use of force in Ukraine is the self-defense of Russia and the collective self-defense for the Donetsk People’s Republic and the Luhansk People’s Republic. Having recognized the two republics as countries, Russia can rely on “intervention by invitation” and on “collective self-defense”—justifications for the use of force that other powerful countries have relied on, including the United States in Iraq and Syria. Russia’s self-defense arguments are laughably weak. More generally, Russia’s reliance on all of these precedents is self-serving, lacking in factual basis and “morally corrupt.” Russia is correct, however, to argue that other powerful countries have undermined international law’s prohibition on the use of force and protections of territorial integrity—even if that argument goes nowhere in terms of a legal or moral justification for Russia’s own actions. To some extent, the prohibition on the use of force has been undermined by efforts to pursue other objectives through international law, in particular human rights and humanitarian ends, particularly in Kosovo and Libya, but to some extent also in Iraq and Syria.

For a century now, a central objective of international law has been to secure interstate peace, but the best ways of doing so are not necessarily clear and they likely extend beyond Article 2(4) of the U.N. Charter. The “long peace” after World War II has led scholars and historians of international law to link interstate peace to the Kellogg-Briand Pact of 1928, which outlawed war, or (more commonly) to the prohibition on the use of force in the U.N. Charter and its roots in the limitations on the use of force in the League of Nations. The sole focus on the early and mid-20th century is misplaced, however. There was a long peace among great powers in Europe following the Napoleonic Wars in the early 19th century, as described in this book-length response to Steven Pinker’s well-known “The Better Angels of Our Nature” (which also describes 1945 as a key turning point marking the decline of interstate war). The long 19th century peace suggests that the relationship between international law and interstate war is more complicated (and fragile) than the standard narrative admits.

Data from political scientists indicates that interstate conflict over territory is more likely than other forms of conflict to escalate into full-scale war, making the invasion of Ukraine all the more troubling. The link between territorial conflict and militarized disputes also, however, suggests that international law may be most effective at generating interstate peace by reducing conflict over territory. Prohibitions on the use of force, such as Article 2(4) of the U.N. Charter, do that, but so do other doctrines of international law, such as uti possidetis, pursuant to which newly independent nations keep the borders they had as colonies. 

The statement of the Kenyan U.N. ambassador condemning the recognition by Russia of the Ukrainian republics speaks to exactly this point:

At independence, had we chosen to pursue states on the basis of ethnic, racial or religious homogeneity, we would still be waging bloody wars these many decades later. … We chose to follow the rules of the Organisation of African Unity and the United Nations charter, not because our borders satisfied us, but because we wanted something greater, forged in peace.

As the statement by Kenya suggests, accepting the territorial status quo has real costs—it reinforces arbitrary and unjust borders. Those costs make uti possidetis unpopular in some quarters. 

The costs of preserving existing borders also fuel efforts to change other areas of international law, including to create a right to self-determination that includes a right of secession for oppressed groups. Russia has relied on remedial self-determination to justify military intervention in Crimea; Western countries used self-determination as part of their argument in favor of the independence of Kosovo from Serbia (a Russian ally). Marko Milanovic describes Russian use of this argument as an example of “a ‘progressive’ theory such as remedial secession/self-determination” being “used for decidedly non-progressive ends, such as justifying territorial conquest.”

International Law: Stronger and More Limited

The European Society of International Law has issued a statement saying in part: “To contend that other States—especially in the West—have no better record when it comes to respecting international law is a morally corrupt and irrelevant distraction.” As observers look ahead to what international law can and should do in the future, the contention is not an “irrelevant distraction.” Instead, the international community must consider how well the norms have worked, who has violated them, and why. Reinvigorated legal commitments to territorial sovereignty and territorial integrity will require an acknowledgment—explicit or implicit—that international law is not strong enough to do everything well. In a perfect world, it could abandon uti possidetis and equitably adjust current borders, it could prevent leaders from harming their own people by relaxing Article 2(4) of the U.N. Charter for humanitarian purposes, and it could empower secession for the truly oppressed despite the territorial integrity of existing states. I have been arguing for years that expanding international law to focus on human rights and humanitarian objectives at the expense of territorial integrity has created credibility and other problems that weaken the international legal system as a whole.

Today, the international community should reinvest in norms of territorial integrity and sovereignty through international law, even at the occasional expense of humanitarian objectives (which should be pursued vigorously through other avenues). The work of the United Nations should focus on interstate peace and territorial integrity. And the international community should think of new approaches to ensuring peace among the world’s most powerful countries. A new “Concert of Powers” modeled after the “Concert of Europe” formed in 1815 is an intriguing idea, one that would bring powerful countries together in an informal forum that offers more space for real dialogue than the U.N. Security Council does. Safeguarding against interstate war is itself an enormous task for international law and international institutions, as the current events in Ukraine demonstrate.

Ingrid Wuerth is the Helen Strong Curry Professor of International Law at Vanderbilt Law School, where she also directs the international legal studies program. She is a leading scholar of foreign affairs, public international law and international litigation. She serves on the State Department’s Advisory Committee on Public International Law, she is a Reporter on the American Law Institute’s Restatement (Fourth) on U.S. Foreign Relations Law, and she is on the editorial board of the American Journal of International Law. She has won Fulbright and Alexander von Humboldt awards permitting her to spend substantial time in Germany and she is an elected member of the German Society of International Law.

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