Case Explained: Toward A Just and Lawful Peace in Ukraine: Part I – Legal Perspective

On the fourth anniversary of Russia’s full-scale invasion of Ukraine, direct negotiations have finally gotten underway. U.S. President Donald Trump’s repeated campaign promise that he could settle the war “in 24 hours” dissolved quickly, as a year elapsed before talks began in Abu Dhabi. Despite the Trump Administration’s wavering support for Ukraine, talks finally commenced only after Russia failed to achieve its goals on the battlefield. At the time of this writing, the two parties are both fighting and talking. Russia continues to launch savage strikes against Ukraine and its civilians on the battlefield, and Ukraine has responded, even as they renew periodic negotiating sessions in Geneva.

The U.S. team, led by Special Envoys Steve Witkoff and Jared Kushner, opened diplomacy with a plan focused narrowly on what could be called “just peace:” a thin proposal pushing Ukraine to accept many of Russian President Vladimir Putin’s demands without meaningful guarantees about territorial integrity, future security, reconstruction, or criminal and civil accountability. Ukrainian President Volodymyr Zelenskyy countered with a more robust 20-point proposal, seeking what could instead be termed “a just and lawful peace:” a durable peace with substantive elements designed to ensure Ukraine’s long-term political, military, and economic future. Western democratic allies have supported Zelenskyy by de facto implementing what Canadian Prime Minister Mark Carney called at Davos “a third way.” This diplomatic plan would seek to avoid on one hand, the “rupture” that plagues the now-fragile post-World War II framework, and on the other, regression to a normatively barren world of great-power spheres of influence. Over time, that European pressure has pushed the U.S.-backed plan in a direction more acceptable to Ukraine.

In a recent interview, Trump announced: “I don’t need international law,” claiming to be bound only by his “own morality.” This two-part article argues that, whatever the U.S. Administration does, the many transnational actors committed to the concept of a“just security” can still infuse legal, human rights, and humanitarian content into the diplomatic framework that houses the Ukraine Peace Process. In Carney’s words, like-minded democracies and nongovernmental groups and individuals committed to “value-based realism” can humanize the Ukraine Peace Process by drawing upon “a dense web of [transnational legal] connections across trade, investment, [and] culture” to build “coalitions that work issue by issue with partners who share enough common ground to act together.”

Part I of this two-part post looks back over the last four years to review what law and lawyers have contributed toward the goal of a just and lawful peace in Ukraine. Part II, which will follow, explores the legal intricacies of a particularly critical piece of the Ukraine puzzle: unlocking frozen Russian assets to finance Ukrainian compensation and reconstruction. Despite claimed legal obstacles and a recent Russian lawsuit, Part II will demonstrate that law poses no barrier to freeing for Ukrainian damages and reconstruction billions of euros in Russian frozen assets that are currently held in Europe.

Ukraine’s Grand Strategy

Over the last four years, many articles in Just Security’s Russia/Ukraine archive have sketched pieces of the emerging Ukraine puzzle. These articles illustrate how the many transnational actors committed to a just and lawful peace can use innovative tools of transnational and international law to infuse human rights and rule of law content into Ukraine policy proposals. Overall, these pieces help illuminate Ukraine’s Grand Strategy, described by one of us at the International Court of Justice just after the invasion as “Putin’s short game is force; [Ukraine’s] long game is law.”

That grand strategy, which diverse transnational actors have promoted over the last four years, revolves around five basic elements:

1. Information: use open sources to show Russia’s illegal actions;

2. Isolation: render Putin an isolated outlaw in an interdependent world;

3. Illegality: demonstrate the illegality of the actions by Putin, his underlings, and his cronies;

4. Diplomacy: when the time is ripe, pursue a Dayton-like peace process;

5. Accountability: in that peace process, preserve criminal and civil accountability in domestic and international fora.

 Collectively, the many “rule of law” players invested in the Ukraine situation have contributed complementary pieces to this vision of a just and lawful peace. Some of the many examples are detailed below.

Global Administrative Law

The post-World War II multilateral framework has generated what one prominent international law school calls “global administrative law”: a network of structures, procedures, and standards for global regulatory decision-making that apply to formal intergovernmental regulatory bodies; informal intergovernmental regulatory networks; and regulatory decisions of national governments and hybrid public-private or private transnational bodies.

Russia’s blatantly lawless actions in Ukraine predictably offend global administrative law. They run afoul of such respected global regulatory bodies as the International Civil Aviation Organization (ICAO), which has an interest in protecting civilian aircraft from shootdowns; the International Atomic Energy Agency (IAEA), which monitors nuclear safety at Ukraine’s Zaporizhia nuclear plant; and the Office of the UN High Commissioner for Human Rights (OHCHR) and UN Human Rights Council (UNHRC), which are dedicated international entities designed to address human rights violations.

For similar reasons, uninsured Russian “shadow fleet” tankers traveling through European waters offend the transparency, participation, and implementation mechanisms of the International Maritime Organization (IMO). The IMO promulgates “generally accepted international regulations, procedures and practices” (GAIRS), to promote “prevention, reduction and control of pollution from ships,” as regulated by rules established by competent international organizations. Along with economist co-authors, two of us (Koh and Davidson) have recently explained how global administrative law may be used to plug gaps in current efforts to choke Putin’s war machine through new, stiffened sanctions that are better able to regulate these shadow fleet operations.

Transnational Public Law Litigation

One of us has framed the various transnational public law litigation efforts undertaken in Ukraine’s legal war. Ukraine’s “full court press” litigation strategy has included three cases before the International Court of Justice (ICJ); four cases under the Law of the Sea Treaty (UNCLOS); five cases before the European Court of Human Rights (ECtHR) in Strasbourg; a World Trade Organization (WTO) case against Russia regarding international trade in transit; and international commercial arbitration regarding the expropriation of Ukrainian assets in Crimea owned by Naftogaz, Oschadbank, Privatbank, and others. In Part II, we clarify how any final judgments rendered through these civil lawsuits can be enforced against immobilized Russian assets.

Accountability Ecosystem/Fragmented Nuremberg

Within this litigation setting, stakeholders have taken important multilateral steps to develop an “accountability ecosystem” for civil enforcement of domestic and international judgments, as well as criminal accountability for both jus in bello crimes and the jus ad bellum crime of aggression. On the civil side, that emerging ecosystem includes efforts by the United Nations General Assembly and the Council of Europe to create a Register of Damages for Wartime Compensation. On the criminal law side, one of us has described how the current complex situation differs from Nuremberg, where all defendants, prosecutors, crimes, and evidence were assembled before a single court. In Ukraine, by contrast, transnational actors have built the case for a “fragmented Nuremberg,” whereby different domestic and international institutions can collaborate to gather evidence for prosecuting both wartime atrocities and the crime of aggression, wherever defendants can be detained and jurisdiction established.

Jus In Bello Crimes

The “fragmented Nuremberg” process has illustrated the much-debated concept of complementarity at work. The Atrocity Crimes Advisory Group for Ukraine, an initiative established by the United States, UK, and EU in May 2022, is advising and assisting Ukraine’s Office of the Prosecutor General (OPG) in investigating and prosecuting atrocity crimes in Ukraine. Meanwhile 43 states parties made a joint referral to ICC prosecutor Karim Khan to try jus in bello crimes committed not just by Putin, but also by Maria Lvova-Belova, Russian commissioner for children’s rights (alleging her responsibility for the war crime of unlawful deportation and transfer of children). Supported by the Biden State Department’s now-defunct Office of Global Criminal Justice (GCJ), Prosecutor Khan separately charged senior Russian military commanders Sergey Kobylash, Sergei Shoigu, and Valery Gerasimov with the war crimes of directing attacks at civilian objects and causing excessive incidental harm to civilians or damage to civilian objects, as well as the crime against humanity of “inhumane acts.” And before the Trump Administration pivoted to its punitive policy of sanctioning high ICC officials and judges, Merrick Garland became the first U.S. Attorney General to visit the ICC to support its Ukraine war crimes investigations.

To further the strategic goal of sharing information regarding these crimes, many sources have created a global focal point for wartime evidence-gathering. The European Union Agency for Criminal Justice Cooperation (Eurojust) has helped to stand up a joint investigative team (JIT) that now consists of Ukraine, six EU Member States, and the ICC’s Office of the Prosecutor. That group has also established a Core International Crimes Evidence Database (CICED), to which hundreds of files from nine countries have been submitted. Ukrainian human rights lawyer Oleksandra Matviichuk and her Center for Civil Liberties won the Nobel Peace Prize for their courageous local evidence-gathering. An impressive public-private information network has emerged from the Ukraine war, linking OHCHR and its Special Rapporteurs with human rights NGOs such as Human Rights Watch and Truth Hounds, investigative organizations such as Bellingcat, and digital crowdsourcing observers such as Conflict Observatory, Yale School of Public Health’s Humanitarian Research Lab, and  eyeWitness.

Those sources collectively document a shocking campaign of Russian atrocities in service of annexation. Even while Putin shifted from his initial short-term invasion strategy of “shock and awe” to a grinding war of attrition, continuing features have included the intentional targeting of civilians through indiscriminate shelling from afar, as in Mariupol and Volnavakha, as well as the up-close brutality of the kind exhibited in Bucha and Izium. At this writing, reliable sources report 1.8 million military casualties (combined Russian and Ukrainian) and 56,550 civilian casualties, with detailed credible reports of torture, sexual assault, summary execution, environmental injury, and the destruction of cultural heritage. There are horrifying accounts of child abductions, “filtration camps,” forced displacement, and the deportation of 1.6 million to Russia or controlled territory through invasive security screenings, family separation and detention, as well as the unlawful use of cluster munitions, incendiaries, hypersonic, and thermobaric missiles.

Rome Statute Article 28(b) declares a superior criminally responsible for crimes “committed by forces under his or her effective command or control,” when that superior “either knew or… should have known that the forces were committing or about to commit such crimes.” Under the “control theory” applied by the ICC in Prosecutor v. Lubanga, direct“smoking gun” testimony is not needed to convict a principal perpetrator who either controls the will of those who carry out the objective elements of the offence or has control over the offence by reason of the essential tasks assigned to them. Putin plainly meets that standard.

These credible allegations have helped to isolate Putin and undermine his claim to be treated as a respected world leader. While ultimate accountability may still be years away, the filing of public charges has restricted Putin’s freedom of movement. Although Trump met Putin in Alaska—unashamedly welcoming a war criminal onto U.S. soil—the rest of the world has largely shut him out. Putin could only travel to Mongolia, an ICC state party, after receiving assurances against arrest. When the (Brazil, Russia, India, China, and South Africa) BRICS and G20 summits convened in South Africa, Putin did not attend, almost certainly because South Africa’s ratification of the Rome Statute legally obligated it to arrest him.

Jus Ad Bellum Crimes

Reasoning that none of these jus in bello crimes would have occurred but for Putin’s original sin of aggression, in June 2025, the EU and Council of Europe established a Special Tribunal for the Crime of Aggression against Ukraine (STCAU) to prosecute top Russian leadership. The Tribunal specifically targets Putin for launching the war, and has been allocated €10 million for its initial work. This hybrid tribunal—which is being set up within the Council of Europe’s framework and will operate independently of, but in cooperation with, the ICC—will become fully operational once a host state agreement is negotiated with The Hague. The International Centre for the Prosecution of the Crime of Aggression Against Ukraine (ICPA), a multinational task force of investigators and prosecutors based in The Hague, has secured crucial evidence to build cases to hold senior Russian political and military leaders accountable for both aggression and atrocities. They plan to prepare cases that can be tried in a variety of jurisdictions, both domestic and international.

The Rule of Law Within Ukraine  

No recounting of the past four years would be complete without also mentioning the concerted efforts the international community has taken to build the rule of law within Ukraine. Recognizing that taking the high road regarding rule of law will be crucial to maintaining Ukraine’s global credibility and support, actors inside and outside Ukraine (here, here, and here) have sought to ensure that despite a long history of corruption, democratic governments of Ukraine in the future will serve the people. These efforts have been illustrated by President Zelenskyy’s insistence, even during wartime, on enacting new anti-corruption laws (although not without controversy) and removing influential high officials accused of corruption.

In the first half of 2025 alone, the National Anti-Corruption Bureau of Ukraine (NABU) and the Specialized Anti-Corruption Prosecutor’s Office (SAPO)—two independent law enforcement agencies established after 2014 to fight high-level corruption—reportedly secured over 50 convictions by actively prosecuting “Operation Midas,” a $100 million energy scandal involving former high-ranking Energy Ministry officials. According to a Transparency International survey, 87% of the Ukrainian people perceive corruption as a widespread phenomenon. As one commentator put it: “these institutions enjoy the broad support of the Ukrainian public and civil society. Indeed, the war with Russia and the war on systemic corruption inside Ukraine are closely related: both are expressions of the stubborn refusal by millions of Ukrainians to surrender their freedom and dignity and of their determination to build a country of which they could be proud.”

A Different Kind of Dayton

In the 1990s at Dayton, the United States brokered a complex multilateral peace accord for the Balkans. As one of us has noted, the Clinton Administration used the “Holbrooke Method”—a novel blend of diplomacy, force, and law—to achieve durable political results. In 1995, force and the threat of force brought the Bosnian protagonists to a historic diplomatic resolution at Dayton engineered by the late Richard Holbrooke, who ingeniously marshalled elements of American hard and smart power to secure a settlement with robust accountability and the force of law. The Dayton Accords have now endured for three decades. But with this U.S. Administration and the resumption of direct Ukraine-Russia talks, can a similar diplomatic result be achieved, backed by law?

President Zelenskyy has said that diplomacy would be more effective with “justice and strength.” Seasoned diplomats have explained (here, here, here, here, and here) how the ongoing direct talks could serve as a vehicle for eventual settlement of this dispute. Ukraine’s military tenacity over the last four years has plainly changed Putin’s calculus. While outmatched in forces, Ukraine has stayed agile, flexible, and high-tech, particularly through use of artificial intelligence. Reportedly, some eighty percent of Russia’s 1 million casualties have been inflicted by AI technology: about three million air, sea, and land drones. By one report, drone attacks have increased by 4,000 percent between 2020 and 2024. As the Russia-Ukraine war has become the first full-fledged AI-driven war—with all its frightening implications (see pp. 16-19)—Ukraine’s military success with AI has only underscored the urgency of moving from soft law declarations to a binding legal instrument setting redlines on the use of AI in modern warfare.

The West’s repeated condemnation of Russia has had the salutary effect of largely keeping China and India on the sidelines. But as his war machine has faltered, Putin has increasingly made reference to suing for peace. How can the world prevent him from winning at the negotiation table what he could not win through aggression and atrocity on the battlefield?

Ukrainian officials report that “the Trump Administration is ramping up pressure on them to make concessions to Russia in a push to end the war by early summer.” Battered by sagging polls, Trump is increasingly pushing for a rushed, hollow peace to buttress his quixotic quest for a Nobel Peace Prize. Europe, however, has pushed back by demanding a more durable peace that infuses the existing framework for negotiation with meaningful rule of law content.

Happily, the talks have moved beyond unproductive Trump-Putin bilateral meetings to “nothing about us without us”: i.e., meaningful Ukrainian participation in any negotiation. In striking contrast to Venezuela—where Trump has chosen to work with the unelected government of Acting President Delcy Rodriguez and expressed little interest in promoting democratic elections—his latest gambit in Ukraine mirrors Putin’s demands, calling for the democratically-elected government to hold elections by May 15, 2026. Although Zelenskyy is a wartime leader under legally declared martial law, and no election can be legally held until peace is achieved, he is reportedly considering holding elections (even though it would accord with Russia’s demands).

The two most contentious issues remain territory and security guarantees. More specifically, these include the status of territory like Donbas, which Russia has not been able to win on the battleground, and whether Ukraine can obtain firm security guarantees from its Western allies—including NATO Treaty “Article 5-like gurantees” or eventual admission to NATO—to prevent Russia from invading it yet again. Urgent implementation questions concern how to move in stages from a cease-fire to a truce, to a durable pact and peacekeeping deployment. A particularly pressing question is whether any truce would be secured by a European peacekeeping force—potentially composed of troops from a “Coalition of the Willing” comprised of the United Kingdom, France, Germany and eight other European countries. If so, questions remain regarding whether and how allies would commit to sustaining Ukraine’s defense capabilities after a settlement is reached.

The most expensive, as-yet unrealized, issue is the creation of a “Ukrainian Marshall Plan” that would encompass aid, reconstruction, and compensation all in exchange for an eventual lifting of sanctions against Russia.  But where would that money come from? Putin is eager to unfreeze frozen Russian assets and have economic sanctions lifted on his terms, simply by ending his campaign of aggression and atrocity without meaningful concessions. Because about $5 billion of frozen Central Bank of the Russian Federation assets are currently being held in the United States, Putin pre-emptively announced his willingness to contribute $1 billion to President Trump’s “Board of Peace” for Gaza, so long as this sum is paid from the frozen U.S.-based Russian assets. But Putin cannot prevail simply by persuading Trump. A vastly larger sum—about €185 (~$217 billion) in frozen Russian state funds and securities—is currently being held by the Belgium-based depositary Euroclear Bank SA/NV.

Nearly two years ago, one of us explained why there are no legal obstacles to accessing these frozen assets as a lawful countermeasure to induce the end of ongoing Russian aggression. As Part II of this post will argue, transferring the frozen assets into negotiated investment funds for Ukraine would fit neatly into President Zelenskyy’s current Peace Plan. Yet some European allies are hesitating to confiscate—or even make loans based on—the frozen Russian assets, apparently troubled by the notion that such a step would pose a “legal problem.”

Part II will explain why these claimed legal obstacles to unlocking billions of euros in Russian frozen assets for Ukrainian damages and reconstruction are illusory. The real problem, we suggest, is not legal limitations, but political will.

***

After four painful years, the broader lesson should be that, even while Russia has waged an inhumane war against Ukraine—which the Ukrainian people have endured with heroic courage and resilience—the law has not been silent. Law and lawyers have accomplished a great deal. A substantial legal architecture for resilience and recovery has developed. International law and lawyers have served as what the evolutionary biologist Stephen Jay Gould called a “Panda’s Thumb”: an ad hoc second-best device to inject law, democracy, and human rights into an emerging collective effort to move beyond just peace to the higher goal of a just and lawful peace. 

This is the constructive goal of what one of us has called the “Yale School of International Law”: to build a more enlightened global system committed to shared interests in both world public order and the promotion of human dignity. As the Ukraine war struggles to resolution, the goal cannot be peace at any price, but a just and lawful peace. Putin’s short game is force; our long game must be law. In playing that long game, we should not minimize the many important steps that already have been taken to erect an architecture of “just security” in Ukraine.

Authors’ Note: Harold Hongju Koh is Sterling Professor of International Law and former Dean at Yale Law School, where he serves as co-director of the Peter Gruber Rule of Law Clinic, of which the other co-authors are members. He previously served as Legal Adviser (2009-13) and Senior Adviser (2021) at the Office of the Legal Adviser at the U.S. State Department, where he previously served as Assistant Secretary of State for Democracy, Human Rights and Labor (1998-2001). He currently advises Ukraine’s Ministry of Foreign Affairs on international law matters. This post reflects the views of him and his co-authors, and not necessarily those of any institution with which Professor Koh is now or has been affiliated.

FEATURED IMAGE: Ukrainian President Volodymyr Zelenskyy speaks at the Diplomatic Conference for the Adoption of the Convention Establishing a Special Tribunal for the Crimes of Aggression Against Ukraine at the Hague on December 16, 2025 (via Council of Europe Media Gallery)