The Russian invasion of Ukraine in February 2022 has sparked an unprecedented and multi-level response to document and investigate the crimes committed during the course of the conflict.

At the domestic level, the Office of the Prosecutor General of Ukraine (OPG) is investigating Russian crimes of aggression and war crimes, as well as crimes against national security, such as treason and collaborative activities. War crimes proceedings were initiated against Russian military personnel, some of them being tried in absentia, and several Russian soldiers that were present at their trials were already sentenced in Ukraine. There has been no sign of criminal investigations or prosecutions of potential war crimes committed by the Ukrainian military.

At the international level, the Office of the Prosecutor of the International Criminal Court (ICC-OTP) opened an investigation on 2 March 2022 on the basis of two ad-hoc declarations lodged by Ukraine in 2014 and 2015. This investigation led to two arrest warrants issued against Vladimir Putin and his Children’s Rights Commissioner Maria Lvova-Belova on 17 March 2023 for the war crimes of unlawful deportation and transfer of children from occupied areas of Ukraine to the Russian Federation. On 4 March 2022, the UN Human Rights Council established an Independent International Commission of Inquiry on Ukraine, which was mandated to investigate alleged violations of international human rights and humanitarian law. At the regional level, the OSCE’s Moscow Mechanism sent missions of experts and has documented war crimes and crimes against humanity, while the EU and the Council of Europe have put in place support and cooperation mechanisms.

In addition, several countries have opened national investigations into the situation, invoking universal or other forms of extraterritorial jurisdiction. Announcements to this effect have been made by states such as Poland, Lithuania, Sweden, Germany, Norway, Switzerland, France, Spain and Canada. To combine accountability efforts, Poland, Lithuania and Ukraine set up a Joint Investigation Team (JIT) in March 2022, which operates under the auspices of Eurojust and was later joined by the ICC-OTP, Estonia, Latvia, Slovakia and Romania. Since the legal framework for prosecuting crimes committed abroad varies greatly from country to country, it is difficult to make general statements about the scope and focus of these investigations. While some countries, such as Germany and Sweden, allow person-specific investigations to be opened without a territorial link, other countries, such as France and Switzerland, require the presence or even the residence of the suspect for doing so. This is why investigations in France, for example, reportedly focus on crimes committed against French nationals, as this does not presuppose such a territorial link.

The investigations currently being conducted by the ICC-OTP, the Joint Investigation Team, the Ukrainian OPG and war crimes units in third states should focus on high-level perpetrators and the structural dimensions of crimes. While prosecuting individual cases certainly sends an important signal in the fight against impunity, the structural patterns of the crimes committed must be at the center of investigative endeavors. The ICC arrest warrants against Putin and his Children’s Rights Commissioner Maria Lvova-Belova are a significant step in that direction, aiming for accountability for the unlawful deportation of Ukrainian children to the Russian Federation. Additionally, a survivor-centered approach must be maintained throughout all stages of investigations that also includes legal and psychosocial support. At the same time, investigating authorities must ensure that civil society perspectives are represented in the prioritization of investigations, with special attention given to marginalized and vulnerable groups of survivors. Ukrainian civil society can draw upon rich experiences and insights with regard to the documentation of war crimes gathered since the beginning of the armed conflict in 2014. It is of utmost importance to listen to their experiences, as well as to support and amplify their voices and demands. Local civil society groups are playing an indispensable role in supporting witnesses and survivors, especially in light of the lack of trust in state authorities that can be observed in many places. Special attention must be given to previously under-investigated crimes, with a focus on sexual and gender-based violence. These investigations must be carried out by specially trained personnel so that re-traumatization and secondary victimization are prevented. Investigations must examine the alleged crimes of all parties to the conflict, some of which date back to the outbreak of the armed conflict in 2014. Within these efforts, the coordination among relevant stakeholders is crucial to avoid the duplication of efforts.

Ukraine must ratify the Rome Statute without further delay, as has long been called for by Ukrainian civil society. Despite having already accepted the ICC’s jurisdiction through two ad-hoc declarations in 2014 and 2015, Ukraine still has not become a party to the Rome Statute. After having undertaken a lengthy process of constitutional amendments that remove alleged legal obstacles to its ratification, there is no reason left not to join the Rome Statute. Nevertheless, Ukrainian officials have repeatedly opposed ratification on the grounds that it would expose Ukrainian armed forces to potential international prosecution. This argument is not only erroneous, as the ad-hoc acceptance of ICC jurisdiction already allows for the prosecution of statutory crimes by all parties to the conflict, but also demonstrates a problematic and one-sided approach to justice. Similarly, Ukraine’s newly introduced domestic framework for cooperation with the ICC leaves fundamental doubts as to its neutrality, with a provision suggesting that cooperation should only apply to crimes committed against Ukraine, rather than to all crimes subject to ICC jurisdiction.

EU states should therefore insist that Ukraine fully commit to impartial justice by ratifying the Rome Statute and make this a precondition for further EU accession negotiations. An important step was taken in 2014 by incorporating the obligation to join the ICC into the EU-Ukraine Association Agreement. Subsequently, however, the EU Commission failed to explicitly include this requirement in the list of steps to be taken to obtain candidate status. While pressure from some EU member states prompted Ukraine to ratify the Istanbul Convention on preventing and combating violence against women and domestic violence, with the aim of removing obstacles to EU accession, the same pressure must be exercised with regard to the ratification of the Rome Statute.

Ukraine must adequately align its legislation with international criminal law. To date, the Ukrainian Criminal Code neither incorporates crimes against humanity nor does it allow for universal jurisdiction and addressing command responsibility. Additionally, existing provisions on war crimes fall short of international standards. Although the Ukrainian parliament adopted a draft law in May 2021 that would fill these gaps, President Zelensky has so far chosen not to sign it, thus obstructing its entry into force. Instead, the Cabinet of Ministers introduced another bill that would only partially implement command responsibility and that lacks provisions on universal jurisdiction.

Also, on the operational level, there are significant doubts regarding the preparedness of the Ukrainian legal system to adequately prosecute international crimes. The first trials against alleged Russian war criminals raised concerns about due process, with exceptionally short proceedings and confessions obtained under unclear circumstances. As much as Ukraine's accountability efforts are to be welcomed and supported, real justice can only be achieved on the basis of laws and proceedings that meet international standards. Ukraine must therefore ensure that these standards are met, in accordance with the demands of Ukrainian civil society.

The principle of universal jurisdiction must be strengthened. Countries with laws that only provide for a limited version of universal jurisdiction, such as France and the Netherlands, need to expand these laws to permit broader jurisdiction in international crimes cases. The ongoing conflict underlines the need for investigations unconstrained by presence requirements of suspects and similar limitations. In the case of the Netherlands, for instance, Dutch war crimes units are not permitted by law to investigate until a suspect is present in the Netherlands, meaning that supporting the ICC with national investigators and forensic experts is the only option available for engaging in investigations that do not meet these narrow requirements.

The crime of aggression is by definition a leadership crime. However, Putin, as long as he remains sitting president, enjoys immunity from prosecution for international crimes before national courts. Similarly, the ICC, which by virtue of its international character would be best placed to prosecute the crime, cannot take actions concerning the Russian war of aggression. It lacks jurisdiction over the crime of aggression when it is committed by nationals of states that are not party to the Rome Statute, such as Russia. A Security Council referral could theoretically bridge that gap, but Russia’s veto is certain. The crime of aggression in this regard is different from war crimes and crimes against humanity, which can be prosecuted when committed on the territory of a state that has either ratified the Rome Statute or accepted ICC jurisdiction through an ad-hoc declaration, as Ukraine has done. This exception goes back to the 2010 Kampala Conference, where the jurisdictional regime for the crime of aggression was specifically negotiated. Powerful states like the US pushed for limiting the court’s jurisdiction over the crime of aggression to shield their own nationals from prosecution. In light of these obstacles, some stakeholders are calling for the establishment of a special tribunal for the crime of aggression.

A special tribunal for the crime of aggression would perpetuate problematic double standards and selective justice, considering that representatives of the same states that once lobbied to limit the jurisdictional power of the ICC regarding this crime are now supporting the idea of such a tribunal. This sends a fatal message that undermines equal justice, implying that aggressive warfare by certain state actors is worthy of prosecution, while the representatives of other states continue to enjoy impunity. The only way to close this impunity gap in an equitable and sustainable manner is to amend the Rome Statute, giving the ICC jurisdiction over all acts of aggression committed against its member states or those who accept its jurisdiction.

Another model for avoiding selectivity would be a hybrid tribunal on all international crimes, as has been demanded by many members of Ukrainian civil society. Such a mechanism would be composed of both national and international professionals and embedded within the Ukrainian legal system. Not only would it be beneficial for furthering international criminal justice but also for strengthening the Ukrainian justice system, enhancing domestic capacities, while ensuring that due process is followed. It would thus provide an adequate answer to the doubts expressed by Ukrainian civil society regarding Ukraine’s domestic capacities to handle cases of mass atrocities.

Victims who have fled to the European Union are entitled to a number of rights under the EU Victims’ Rights Directive, even if the crimes were committed outside the EU. As part of the ongoing investigations in many European countries under the principle of universal jurisdiction, victims should be fully informed about their rights under the directive and how they can best exercise them. This includes low-level access to legal and psychosocial support. Legal support should include advice on war crimes investigations, witness protection, as well as on migration status and related questions. Such forms of support would mitigate the risk of duplicating survivor interviews by ensuring that survivors in stable conditions would provide better quality testimonies. However, there are no adequate support mechanisms in place across Europe either for victims of international crimes from Ukraine or other countries.