“Justice and accountability are central pillars of the United States’ policy on Ukraine,” the White House stated in February 2023 marking the one-year anniversary of the Russian invasion.Footnote ¹ Indeed, the United States has backed a wide range of international and domestic mechanisms, seeking to leverage their different expertise, capabilities, and authorities, to investigate and prosecute Russians for war crimes, crimes against humanity, and the crime of aggression, all of which the Biden administration has explicitly accused Russia of committing.Footnote ² The administration's approach has been inclusive, encouraging international factfinding by human rights bodies and civil society organizations, endorsing the International Criminal Court's investigations and its issuance of an arrest warrant for Russian President Vladmir Putin, enabling accountability efforts across Europe through cooperative arrangements, and supporting Ukraine's justice system, providing its investigators, prosecutors, and judges with training, technical assistance, funding, and evidence. “There is no hiding place for war criminals,” U.S. Attorney General Merrick Garland said in June 2022, reflecting this all-encompassing strategy.Footnote ³ “The U.S. Justice Department,” he averred, “will pursue every avenue of accountability for those who commit war crimes and other atrocities in Ukraine.”Footnote ⁴

The U.S. focus on individual criminal accountability began at the very start of the war. On March 3, 2022, the United States and forty-four other countries and Ukraine invoked the Organization for Security and Co-operation in Europe's (OSCE) Moscow Mechanism.Footnote ⁵ A three-person group of independent experts was appointed whose mandate was to “[e]stablish the facts and circumstances surrounding possible contraventions of OSCE commitments, and violations and abuses of international human rights law and international humanitarian law; [and] [e]stablish the facts and circumstances of possible cases of war crimes and crimes against humanity . . . with a view to presenting [the information] to relevant accountability mechanisms.”Footnote ⁶ The United States and other states subsequently invoked the mechanism twice more in connection with the invasion of Ukraine: on June 2, 2022 (to follow-up on the report of the first expert group) and on March 20, 2023 (to focus on “the forcible transfer of children within parts of Ukraine's territory temporarily controlled or occupied by Russia and/or their deportation to the Russian Federation”).Footnote ⁷ The three reports documented extensive violations of international humanitarian law and international human rights law by Russian forces.Footnote ⁸

At the same time as the initial resort to the Moscow Mechanism, the United States, working with other members of UN Human Rights Council, helped establish the Council's Independent International Commission of Inquiry on Ukraine (COI).Footnote ⁹ The COI's mandate provides that it will “investigate all alleged violations and abuses of human rights and violations of international humanitarian law”; “collect, consolidate and analyse evidence of such violations and abuses . . . [and] systematically record and preserve all information”; “document and verify relevant information and evidence . . . [and] cooperate with judicial and other entities”; “identify, where possible, those individuals and entities responsible”; and “make recommendations, in particular on accountability measures.”Footnote ¹⁰ In its two reports issued to date, the COI has found that “war crimes and violations of human rights and international humanitarian law have been committed in Ukraine since 24 February 2022 . . . [and that] Russian armed forces are responsible for the vast majority of the violations identified.”Footnote ¹¹ Additionally, the United States has financially supported the Office of the High Commissioner for Human Rights’ UN Human Rights Monitoring Mission in Ukraine, which “has verified numerous allegations of arbitrary deprivation of life, arbitrary detention and enforced disappearance, torture and ill-treatment, and conflict-related sexual violence (CRSV).”Footnote ¹²

Also at the international level, the United States has backed the referral of the situation in Ukraine to the International Criminal Court (ICC). Taking a starkly different approach to the court than that of the Trump administration,Footnote ¹³ Ambassador-at-Large for Global Criminal Justice Beth Van Schaack stated that the “ICC occupies an important place in the ecosystem of international justice, and the United States supports the investigation by the ICC Prosecutor.”Footnote ¹⁴ President Joseph R. Biden, Jr. described the ICC's arrest warrant for President Putin for war crimes as “justified.”Footnote ¹⁵ Congress's attitude toward the ICC has changed too. A Senate resolution referred to the ICC as “an international tribunal that seeks to uphold the rule of law, especially in areas where no rule of law exists.”Footnote ¹⁶ To allow the United States to assist the ICC in its investigations and prosecutions related to the situation in Ukraine, the American Servicemembers’ Protection Act of 2002 was amended in December 2022.Footnote ¹⁷ The United States may now assist with the ICC's Ukraine investigations and prosecutions of non-U.S. nationals, fund those investigations and prosecutions, and permit the ICC to conduct investigative activities in the United States regarding those foreign nationals.Footnote ¹⁸ Cooperation with the ICC, however, has been impeded thus far by the Defense Department.Footnote ¹⁹

Though supporting these international institutional modes of establishing accountability, the United States has understood from the start that the bulk of investigations and prosecutions of Russian atrocities would be conducted by Ukrainian authorities. A month after the invasion, President Biden announced the launch of the European Democratic Resilience Initiative (EDRI) to help ensure “democratic resilience, advance anti-corruption efforts, and defend human rights in Ukraine and its neighbors in response Russia's war of aggression.”Footnote ²⁰ The United States, along with the European Union and the United Kingdom, created the Atrocity Crimes Advisory Group (ACA) on May 25, 2022, to support the War Crimes Units of the Office of the Prosecutor General of Ukraine (OPG), including by sending investigators and prosecutors to Ukraine.Footnote ²¹ The United States has provided $10 million to assist the OPG in “documenting, preserving, and analyzing evidence of war crimes and other atrocities committed in Ukraine, with a view to criminal prosecutions” and an additional $10 million to “deploy experts and other key partners in support of the OPG.”Footnote ²² The Departments of State and Justice have also “provide[d] training and mentoring, including on tactical and criminal investigative assistance and forensics and evidence collection,” to the National Police of Ukraine and the State Border Guard Service.Footnote ²³ The United States Agency for International Development (USAID) has conducted a joint training program with Ukrainian government lawyers at the Ministry of Justice, the Ministry of Foreign Affairs, and the OPG on “methods for collecting evaluating, and synthesizing evidence in line with relevant admissibility rules” of international tribunals.Footnote ²⁴ The Department of Justice has also provided training to Ukrainian authorities to “address[] the needs of surviving victims and for facilitating their participation in the investigative and prosecutorial processes.”Footnote ²⁵

Bilateral assistance between the United States and Ukraine was enhanced with the signing on September 20, 2022, of a memorandum of understanding (MOU) between the Department of Justice (DOJ) and the OPG.Footnote ²⁶ The MOU allowed the two agencies “to work more closely together to identify, apprehend, and prosecute individuals involved in war crimes and other atrocities in Ukraine” by “facilitat[ing] appropriate cooperation, coordination, and deconfliction between each country's respective investigations and prosecutions” through “removing barriers to timely and effective exchanges of information and evidence . . . and increasing the ease with which technical cooperation may be provided.”Footnote ²⁷ DOJ is also working and coordinating with European partners through the European Union Agency for Criminal Justice Cooperation's (Eurojust) Joint Investigation Team (JIT) and the International Centre for the Prosecution of the Crime of Aggression Against Ukraine (ICPA), hosted at Eurojust, to which it will detail a prosecutor.Footnote ²⁸ The Department of Justice's assistance efforts were centralized in June 2022 with the creation of the War Crimes Accountability Team, which was tasked with “hold[ing] accountable those who have committed war crimes and other atrocities in Ukraine.”Footnote ²⁹

In addition to supporting Ukraine's accountability processes, the United States is also promoting proceedings in other national jurisdictions. At home, DOJ's Human Rights and Special Prosecutions Section is investigating “Russians suspected of war crimes against one or more Americans.”Footnote ³⁰ The United States has imposed sanctions “on those engaged in human rights abuses and exercising illegitimate authority in occupied areas of Ukraine,”Footnote ³¹ and it has also imposed “expansive visa restrictions on members of the Russian military and others committing human rights abuses related to Russia's war.”Footnote ³² The United States is also aiding “strategic litigation in other courts around the world,” including “through memoranda of understanding with different states, through engagement with the [JIT], and by working with civil society organizations that are providing potential evidence to national authorities.”Footnote ³³

The ICPA notwithstanding, the international and domestic investigative and prosecutorial mechanisms in operation thus far have focused primarily on crimes against humanity and war crimes, not the crime of aggression.Footnote ³⁴ The ICC cannot proceed against Russian nationals for that crime since Russia is not a party to the Rome Statute.Footnote ³⁵ And international law provides immunity to heads of state from national prosecutions in other countries. Various proposals have been put forward to establish a jurisdiction that could prosecute Russians for the crime of aggression. Ambassador Van Schaack announced in March 2023 that the United States “believe[s] an internationalized court that is rooted in Ukraine's judicial system, but that also includes international elements, will provide the clearest path to establishing a new Tribunal and maximizing our chances of achieving meaningful accountability.”Footnote ³⁶ Those “significant international elements” would include “substantive law, personnel, information sources, and structure,” and the tribunal “might also be located elsewhere in Europe, at least at first, to reinforce Ukraine's desired European orientation, lend gravitas to the initiative, and enable international involvement.”Footnote ³⁷ “A tribunal with these features,” she subsequently told the Senate Judiciary Committee, has “a clear legal basis under international law that respects the UN Charter.”Footnote ³⁸ “It is also the one,” she continued, “most likely to garner widespread and diverse international support.”Footnote ³⁹ “By rooting the court within Ukraine's judicial system,” she explained, “international investment will not only capacitate accountability for the crime of aggression, but it will also enhance Ukraine's own domestic processes, further institutionalize the rule of law, and enable multiple forms of international support that will have a lasting impact for generations thereafter.”Footnote ⁴⁰ The United States has pushed back against an alternative model for prosecuting aggression that is endorsed by Ukraine: a special tribunal on the crime of aggression created by the UN General Assembly.Footnote ⁴¹