The Role of the International Accountability Mechanisms

Investigation by the Office of the Prosecutor of the International Criminal Court

Ukraine has a long and complicated relationship with the International Criminal Court. On 20 January 2000, Ukraine signed the Rome Statute of the ICC. In the following year the Constitutional Court of Ukraine decided that Ukraine could not ratify the Rome Statute as it contradicted Article 124 of the Constitution of Ukraine as a complementary to the national justice institution[455].

Following the Revolution of Dignity in 2013 and the outbreak of the armed conflict in Ukraine, there had been increasingly frequent discussions among government officials at various levels about engaging the International Criminal Court in the investigation of those events. As a result, the Verkhovna Rada of Ukraine adopted two declarations recognising the Court's jurisdiction. The first declaration concerned the events of Maidan between 21 November 2013 and 22 February 2014[456]. The second concerned the consequences of the armed conflict on the territory of Ukraine in relation to the annexation and occupation of Crimea and armed hostilities in Donetsk and Luhansk regions[457]. As the second declaration covered the period from 20 February 2014 with no end date, the ICC also has jurisdiction over events after 24 February 2022. The declaration specifically draws attention to the actions of ‘...senior officials of the Russian Federation and leaders of the terrorist organisations “DPR” and “LPR”...’[458].

Despite the fact that the Office of the Prosecutor of the ICC had been presenting its preliminary conclusions on the situation in Ukraine since 2015, the issue of joining the ICC as a full-fledged state party had not been on Ukraine’s political agenda for many years. However, during the negotiations on Ukraine's membership in the European Union, the ratification of the Rome Statute was identified as one of the key conditions. On 16 September 2014, the Association Agreement between Ukraine and the European Union and the European Atomic Energy Community was ratified[459]. Article 8 of the Agreement stipulates that ‘The Parties shall cooperate in promoting peace and international justice by ratifying and implementing the Rome Statute of the International Criminal Court (ICC) of 1998 and its related instruments’. In response to this provision, the Ukrainian Constitution was amended in 2016 to enable the consideration of the ratification of the Rome Statute. This amendment entered into force on 30 June 2019[460]. Although the need to join the ICC has been discussed at the legislative level multiple times since 2019, it is yet to happen. The key reservation against ratification is that the Ukrainian military is against ratification along with various other excuses. One of the most recent official decisions of the Ukrainian government states that the issue of ratification of the Rome Statute will be considered within one year after the end/termination of martial law in Ukraine[461].

On 2 March 2022, the ICC Prosecutor opened an investigation into the situation in Ukraine following the referral by 43 ICC states parties pursuant to Article 14 of the Rome Statute[462].

Since March 2022, the ICC Prosecutor Karim A.A. Khan KC has already visited Ukraine five times[463]. The ICC investigators are working directly in the field, with a total of 42 investigators, experts, and other Court personnel were deployed to Ukraine[464]. In particular, these include experts from the Netherlands provided by the country in support for the ICC investigation. All communication between the Office of the ICC Prosecutor and the Ukrainian authorities is carried out through the Office of the Prosecutor General, following the amendments to the Criminal Procedure Code of Ukraine[465].

In March 2023, the ICC issued arrest warrants for Vladimir Putin and Maria Lvova-Belova on charges of alleged war crimes, namely the unlawful deportation and unlawful transfer of children from Ukrainian territory to the Russian Federation under Articles 8(2)(a)(vii) and 8(2)(b)(viii) of the Rome Statute[466]. In March 2023, an agreement was signed to open a "field office" of the International Criminal Court in Ukraine[467].

On March 5, 2024, Pre-Trial Chamber II of the Court issued new arrest warrants for the systematic attacks on energy infrastructure between 10 October 2022 and 9 March 2023 as war crimes under Articles 8(2)(b)(ii), 8(2)(b)(iv) and crimes against humanity under Article 7(1)(k) of the Rome Statute[468].  On June 24, 2024, as part of the investigation into these facts, Pre-Trial Chamber II of the Court announced two new arrest warrants for Sergei Shoigu and Valery Gerasimov[469]. 

The key milestone for Ukraine's cooperation with the ICC was the ratification of the Rome Statute and its accession to the Court's system as a full-fledged state party on 1 January 2025[470]. When ratifying the Rome Statute, Ukraine also made a declaration under Article 124 of the Statute. The ratification law states: ‘Ukraine declares that, for a period of seven years after the entry into force of the Rome Statute for Ukraine, it does not recognize the jurisdiction of the International Criminal Court over the crimes set forth in Article 8 (as amended) when the crime is alleged to have been committed by its nationals’[471]. It should be noted that Article 124 was deleted by the Assembly of States Parties back in 2015, as it did not comply with the spirit of the Statute and threatened to deprive victims of justice[472]. However, the amendment did not enter into force because it did not receive the required number of signatures. The implications of this article remain uncertain and depend on the Court's interpretation and decision.  

The International Criminal Court remains the main accountability mechanism for grave crimes committed in the territory of Ukraine. Its investigation of the Ukraine situation is of interest not only to Ukraine but also other states. Additional financial support and engagement of experts from other countries to assist the investigation create an expectation of tangible outcomes from the ICC for this situation. At the same time, it is important to objectively assess the Court's capacity pertaining to its work in Ukraine:

The Court's jurisdiction over Ukraine excludes the crime of aggression

— Considering the requirements of the Rome Statute as well as strict limitations of the Kampala Amendment, the Court cannot consider the crime of aggression committed against Ukraine. The ICC Prosecutor also explicitly mentioned these constraints in his statement on the opening of the investigation[473].

The ICC does not have the resources to investigate all the crimes committed in Ukraine

— According to the statistics of the Ukrainian authorities, alleged violations of international criminal and humanitarian law in Ukraine are recorded daily and number is in the hundreds of thousands. Taking into account the Court's capacity, one cannot say that it will investigate absolutely all grave international crimes. The most optimistic forecasts suggest that the ICC will take up to five cases, but further consideration of other crimes will be left to either Ukraine’s domestic system or a special accountability mechanism should one be established in future[474].

It is unclear which individuals will be prosecuted by the Court

— Ukraine expects that the ICC will be able to prosecute senior officials of the Russian Federation, referring to the fact that ‘their immunity is irrelevant to the prosecution by the Court.’[475] The court’s updated policy on situation completion takes into account the availability of perpetrators to stand trial. Therefore, potentially, when identifying potential perpetrators before the ICC, it is possible to consider not only top, but also mid-level perpetrators, but ultimately will depend on the possibility of execution of arrest warrants issued by the Court[476]. At the same time, the progress of the cases of persons covered by the arrest warrants depends on their detention and transfer for further prosecution by the Court. Despite the fact that the ICC is currently considering the possibility of resolving certain proceedings in absentia, these proceedings will not cover the consideration of the merits of the case without the accused.

Cooperation of the ICC with Ukrainian authorities has a number of obstacles under national legislation of Ukraine

—  On 3 May 2022, the Criminal Procedure Code of Ukraine was amended to include provisions on cooperation with the International Criminal Court[477]. The ability of the Office of the ICC Prosecutor to collect evidence, access crime scenes, approach witnesses and detainees is carried out within the constraints determined by Ukrainian law and in accordance with the procedures established for investigations in Ukraine. Ukraine’s often restrictive regulations (such as the powers of the Prosecutor General to ultimately decide whether the ICC investigators will have access to the necessary information) may adversely affect Ukraine's cooperation with the ICC and jeopardise the quality of the ICC’s investigation.‍

Communication on behalf of Ukraine and the ICC is carried out by the Office of the Prosecutor General, with various structural units involved in the process.

— The issue of international legal cooperation is under the authority of the relevant department at the Office of the Prosecutor General, which in turn has a separate unit for cooperation with the ICC. In addition, specialised unit within the War Crimes Department of the OPG is tasked with responding to the requests from the OTP of the ICC which they receive in relation to the investigations the Department is responsible for. There is also a unit that ensures cooperation with the JIT, which includes the ICC among their members. The coherency of internal communication processes within the OPG also affects the nature of its cooperation with the Court, given the scope of powers vested in the Prosecutor General in this domain. On the other hand, the excessive powers of the Prosecutor General to decide on granting the ICC staff permission to conduct procedural actions in Ukraine means there is broad scope for arbitrary decision-making.

The Court needs to continuously attract additional resources to conduct investigations.

— Every year, the Assembly of States Parties to the ICC approves the Court's budget for the following year, which allocates funds depending on the workload in the situations of ongoing investigations and preliminary examinations. States which referred Ukraine’s situation to the ICC so far have been supporting the Court's investigative efforts. But this support has mostly been by way of voluntary contributions rather than increasing the Court's regular budget in proportion to the number of investigations and overall resources required and secondments. For example, the Netherlands sent its own experts to join the team of investigators from the Office of the ICC Prosecutor in Ukraine[478]. The continuation of the ICC’s work in Ukraine will require the continued support of States Parties, both in terms of expertise and funding[479]. Voluntary contributions make the ICC vulnerable and dependent on the will of the states; moreover disproportionate distribution of the resources internally results in some of the Court’s organs lacking the capacity to perform their functions in accordance with their mandate.

The ICC is vulnerable to external sanctions which may be imposed by powerful non-States Parties.

— On 6 February 2025, the US President issued an executive order ‘Imposing sanctions on the International Criminal Court’, which stipulates the imposition of sanctions against the ICC for investigating, prosecuting, detaining or arresting representatives of the United States or its allies, unless these states have consented to the relevant jurisdiction and actions of the Court[480]. The decision was made in connection with the arrest warrants issued by the ICC against Benjamin Netanyahu and Yoav Gallant[481]. The first person to be sanctioned under President Trump's order was ICC Prosecutor Kareem Khan. On 9 January, the US House of Representatives supported the bill H.R.23 ‘Illegitimate Court Counteraction Act’, which provides for broad sanctions against the Court. It was later passed to the Senate and ultimately failed to be adopted[482]. This draft law, however, may again be submitted for consideration and adopted in parallel with the US President executive order.It is difficult to fully assess the extent of the negative impact of sanctions on the ICC, in particular given that their scope may change over time. In any case, they impede the ICC's investigations in all situations, including Ukraine, and jeopardise its political legitimacy[483]. The further functioning of the Court will depend on the support of the states parties to the Rome Statute, in particular the EU countries, which must ensure the full functioning of the institution, the availability and use of financial resources, and cooperation with service providers[484].

JIT Investigations

The work of joint investigation teams is one of the forms of cooperation between states in criminal proceedings[485]. The legal basis for such collaboration is set out in the Second Additional Protocol to the European Convention on Mutual Assistance in Criminal Matters[486]. According to its provisions, a joint investigation team may be set up, in particular, in situations where: a State Party’s investigations into criminal offences require difficult and demanding investigations having links with other Parties; a number of State Parties are conducting investigations into criminal offences in which the circumstances of the case demand coordinated, concerted action in the State Parties involved. At the same time, it is necessary to have a clear understanding of the objectives and purpose of the investigation, as well as the process and location of the prosecution based on its outcomes.

Following 24 February 2022, Ukraine allegedly decided to use the successful experience of the JIT in the case of the МН17 crash[487], but in relation to the international crimes committed as a result of the full-scale invasion. On 26 March 2022, the Prosecutors General of Ukraine, Poland, and Lithuania signed an agreement to establish a joint investigation team into alleged war crimes and crimes against humanity on the territory of Ukraine. According to the Office of the Prosecutor General, the JIT will focus on the collection, secure storage and rapid exchange of information and evidence of war crimes collected during investigations in the territory of the participating countries, as well as criminal intelligence[488]. Eurojust has supported the agreement and emphasised that joining was open to all EU member states[489]. At the time, the then Prosecutor General, Iryna Venediktova, called on other countries that had also opened investigations into the situation in Ukraine to join the JIT. On 25 April 2022, the Office of the ICC Prosecutor joined the JIT as an observer[490]. In addition, Estonia, Latvia, and Slovakia also became members of the JIT on 31 May 2022[491]. Romania also joined the JIT on 13 October 2022[492] and Europol in 2023[493]. States which have the most substantive and consistent experience in investigating and prosecuting grave crimes under the principle of universal jurisdiction, such as Germany, the Netherlands, France, Switzerland did not join the JIT.

On the part of Ukraine, structural investigation, which includes all the recorded incidents of the full-scale invasion of Ukraine by the Russian Federation, is investigated in the framework of the JIT. As reported by the Office of the Prosecutor General at the time of the establishment of the JIT, cooperation between the countries should include interviewing individuals who left the territory of Ukraine as a result of the armed conflict and seizing property of those involved in war crimes committed on the territory of Ukraine[494]. The investigations by other countries also pertain to the allegations of international crimes committed as a result of the armed conflict in Ukraine without focusing on individual cases.

The JIT has indeed become a rather large entity whose work requires clear guidelines at the level of a joint agreement. As an example, the JIT that investigated the МН17 case, was set up to investigate a concrete incident and it set the following as the objectives of its work: to identify those responsible for the downing of the flight and to gather evidence for the prosecution of those responsible. The countries agreed that Dutch standards would be applied to the investigation, and that cooperation between the countries allowed the Dutch and Australian investigators to conduct investigative actions in Ukraine's territory together with Ukrainian authorities[495]. No such agreement in the case of the current JIT is publicly available. 

The efficiency and effectiveness of the JIT ultimately depends on a clear vision of its end goal and a strategy that can ensure concrete results. Presently there does not appear to be an end goal clearly defined nor is there a strategy. The aim has been defined as “to facilitate investigations and prosecutions in the States concerned, as well as those that may be taken forward to the ICC”[496]. To this end JIT member States document the information from Ukrainian refugees and OSINT. Although the ICC is mentioned as a mechanism which could use the information, it is clear that the ICC will only be able to use limited information collected by the JIT states only pertinent to their investigations. In addition, there is no clarity as to the procedural standards which are used by different states to collect the information. Although the European Network for Investigation and Prosecution of Genocide, crimes against humanity and war crimes (‘Genocide Network’) is playing the role of the coordinator, members of the JIT use their own legislation as a legal basis for documentation which means that investigative standards used by different states within the JIT also differ. This may affect the quality of the information collected and its status as potential evidence, depending on where the documented crimes will ultimately be prosecuted. In order to clearly identify the ultimate role of JIT and its added value in the myriad of various accountability initiatives there needs to be an overall strategy and vision of the justice and accountability architecture for the situation in Ukraine.

The establishment of the JIT in such a format with the Prosecutor of the ICC and Europol as participants has been unprecedented in many respects. Ukraine has been put in a rather challenging situation as a result of non-ratification and non-implementation of the Rome Statute, which means that its procedural standards remain unaligned with the rest of the JIT members. Furthermore, Ukraine is not a member of Eurojust or Europol. Consequently, there are questions as to its access to information that has been collected and documented by other JIT’s member states, but also the use of its information in the domestic proceedings, bearing in mind that Ukrainian legislation does not allow the use of information collected and/or stored by third parties, such as Core International Crimes Evidence Database (CICED)[497].

International Centre for the Prosecution of the Crime of Aggression (ICPA)

Russia’s war of aggression against Ukraine has been a raison d’etre of the negotiations between Ukraine and the international community as to the possible options for prosecuting the crime of aggression. While no final solution had been made at that time, on 3 July 2023, a first step towards it was taken when the ICPA was opened in The Hague. The Centre brings together prosecutors from different countries, not only from the JIT participating states. In particular, the U.S. government has appointed a special prosecutor for the crime of aggression to assist the Centre. The Centre operates with the support of Eurojust, which also administers the evidence database that is filled and analysed as part of its work. It is not yet clear by which accountability mechanism the Centre’s evidence will be used, but the Ukrainian side believes that its activities will reinforce the future mechanism(s) for prosecuting the crime of aggression.

In March 2025, the news broke that the United States had withdrawn its representatives from the Centre. It remains difficult to assess how this affected its work.

Against the backdrop of active discussions and the development of documents related to the establishment of a special tribunal for the crime of aggression against Ukraine, the Centre continued its work, developing its own approach to identifying potential subjects for future criminal prosecution. At the same time, the Centre itself is not involved in the preparatory work for establishing the tribunal.

Currently, the progress of the work of ICPA is stalled because of the lack of legal basis for collecting evidence of the crime of aggression: it is unclear which definition of the crime of aggression to be used when documenting evidence for future prosecutions. On the one hand there is article 437 of CCU and broad definition of a “perpetrator” proposed by the Supreme Court's most recent decision (see section Overview of Ukraine’s Domestic Legislation) on the other hand there is a Rome Statute and the UN resolution 3314 which gives a polar opposite definition (highest level of political and military leadership with decision-making powers). This challenge will be solved once there is a consensus reached on the kind of accountability mechanism which will be mandated to prosecute the crime of aggression in the case of Ukraine.

Investigations by states under the Principle of Universal Jurisdiction

The implementation of the principle of universal jurisdiction (UJ) has become one the forms of international support for justice related processes in Ukraine. In total, according to official reports, 26 countries have launched investigations into the alleged international crimes as a result of the Russia's full-scale invasion of Ukraine[503].

The principle of universal jurisdiction enables other states to investigate grave international crimes that have been committed beyond their borders. Although it can be a powerful tool for ensuring justice and accountability for the most serious crimes, investigations and prosecution under this principle come with its own set of challenges, rooted not only in the complexity of prosecuting grave crimes, but also country specific legislation and prosecutorial strategies, priorities and capacities of each national justice system. From Ukraine’s perspective the following challenges have already become apparent:

States’ Experience in Prosecuting Grave Crimes

Many states that have opened investigations have not had much experience in investigating and prosecuting grave international crimes. On the one hand, there are states like France, Germany, Sweden, and the Netherlands, that have a developed state practice, methodology, strategies and case law related to war crimes charges, crimes against humanity, and even genocide. These states have dedicated units within their law enforcement agencies that have long been working with cases similar to those being committed in Ukraine and have opened either structural or individual investigations (France, Germany, Lithuania) involving their own nationals as victims. 

On the other hand, countries such as Poland, Lithuania, Latvia, and Slovakia, despite having a universal jurisdiction provision in their national legislation, lack a solid practical experience in using it. They mostly focus on collecting information as part of their structural investigations from Ukrainian refugees who temporarily settled in those states. They also have access to Europol, Eurojust where they can all exchange information, use databases and coordinate with one another.

Constraints of the Principle of Universal Jurisdiction Application

Each country has its own set of rules and limitations pertaining to the prosecution of grave international crimes. For instance, some states like France have only opened incidents specific investigations involving French nationals in order to prosecute under the principle France requires for war crimes, crimes against humanity and genocide residence ties with the alleged perpetrator. Same is true for Austria[504]. Switzerland subscribes to the “conditional” or “limited” conception of universal jurisdiction, the exercise of which is subject to two conditions: (a) The presumed offender is in Swiss territory; (b) The presumed offender has not been extradited to another competent jurisdiction[505].

The US now has similar legislation to that of Germany and Sweden following the adoption of the Justice for Victims of War Crimes Act (JVWC) in 2023[506]. The JVWC changed the scope and reach of the United States' ability to prosecute war criminals. There no longer needs to be the US nationality of a victim or a perpetrator link and anybody who commits a war crime anywhere in the world can be prosecuted by the United States if they are present there. The new law also removed the statute of limitations, although without the retroactive effect. There is no possibility of prosecution for crimes against humanity or the crime of aggression as it is only limited to war crimes[507].

Furthermore, the majority of the European, with the exception of France for instance, and the US national criminal law systems do not permit in absentia trials as their greatest risk is failure to ensure the right of an accused to fair trial, hence the requirement of the accused’s presence or nationality or residence link in some jurisdictions to the prosecuting state.

Some states appear to have more progressive UJ laws than others, in principle, allowing the victims to have a direct access to a pre-trial judge through civil party application or requiring only the presence and availability of victims and witnesses to enable the authorities to take direct testimonies. However, the reality differs, in so far as lengths to which states are willing to go to physically secure individual perpetrators to ensure they stand trial there. On the one hand, naturally, it is an issue of available resources but on the other, it is their willingness and intention to dedicate those resources, not only of their units, but of the official and covert police and intelligence networks.

Issue of Resources

Ultimately intention and resources are the driving and ultimate factor when states set the rules and make a call as to whether open investigations under the UJ principle or not. One example, Germany having tested different strategies in various other situations, for instance, when prosecuting members of the ISIS for the crimes against yazidis decided, that unless there was a very good prospect of the execution of an arrest warrant, it will not be opening individual investigations even if the victims reside in Germany and available for investigative actions[508]. Typically units are small and have a very limited capacity, therefore investing in individual investigations as opposed to structural ones that are unlikely to result in successful prosecutions would not be a step states would be willing to take often.

Even structural investigations require substantial resources (time, funding, human resources). For instance, by September 2022, the Minister of Justice of Poland reported that they had already interviewed 1,200 refugees in the country and while the war rages on in Ukraine, the number of victims of and witnesses to the atrocity crimes who continue to flee grows[509]. Therefore, states which collect information from the victims, should also conduct some outreach activities to manage the victims expectations in relation to the prospects of opening investigations based on their reporting of crimes.

Principle of Complementarity and Principle of Universal Jurisdiction

One argument in favour of states applying a universal jurisdiction principle to be more decisive and proactive is that provided they are states parties to the ICC they are expected to act in the spirit of the Rome Statute by adhering to the principle of complementarity. In such a case effective coordination becomes key to managing all the ongoing investigations by different states also vis-a-vis the ICC investigation of the Ukraine situation. There is an obligation in the CCU to investigate every crime[510]. Ukraine opens investigations into every single incident regardless of whether it is being investigated by other states or other institutions. National investigations under the universal jurisdiction principle, therefore should complement both Ukraine’s and the ICC’s efforts in those instances, where both lack capacity. Insufficiencies of the Ukrainian legislative framework means that states’ investigations operate on different levels of quality and capacity altogether and therefore, coordination and cooperation of all states and institutions involved becomes even a greater challenge. Moreover, should investigations under the principle of universal jurisdiction result in successful arrest warrants and Ukraine will decide to request an extradition, there will also be a dilemma of Ukraine’s capacity to ensure impartial, objective and fair trials.

Assistance from Other States

Although the armed conflict in Ukraine has been ongoing since 2014, official reports from state authorities on international assistance from other countries only began to appear after 24 February 2022. For instance, several missions of French experts worked, inter alia, on collecting evidence in Kyiv region[511] and were involved in investigating events in Kharkiv region[512]. France also donated a mobile DNA laboratory to the Office of the Prosecutor General and trained ten Ukrainian experts in the use of the provided materials and equipment[513]. In addition, forensic experts from Slovakia[514] and Polish experts worked in Ukraine to examine the sites affected by shelling in Kyiv, Mykolaiv and Borodianka[515].

Rules governing engagement and participation of experts are contained in the Criminal Procedure Code of Ukraine which does not provide for such a procedure of providing international assistance to Ukrainian law enforcement as visits of foreign experts to Ukraine. Despite public expressions of support of this format of cooperation, the evidence obtained by these experts is inadmissible in official proceedings. Thus, for instance, findings from mobile DNA laboratories must undergo forensic verification by the state approved forensic examination centres, the conclusion of which can then be included in the case file[516]. In practice, investigators and prosecutors do not understand how to properly and officially utilise all such international assistance.

Another permanent form of assistance to Ukrainian law enforcement agencies with investigations was established by the United States of America, the United Kingdom, and the European Union[517]. The Atrocity Crimes Advisory Group (ACA) for Ukraine was established to support the Office of the Prosecutor General[518]. The primary objective of the group is to streamline coordination and communication efforts to ensure implementation and development of best practices, avoid duplication of efforts, and encourage the expedient deployment of financial resources and skilled expert personnel to respond to the needs of the OPG as their beneficiary. The ACA activity is composed of the following elements: the work of the Advisory Group to the OPG, made up of experienced war crimes prosecutors, investigators, military analysts, forensic specialists, and other experts based in the region on a permanent basis; Mobile Justice Teams composed of both international and Ukrainian experts, which are created and deployed to increase the capacity of the OPG War Crimes Unit and regional prosecutors to conduct field investigations. The teams are[519].

The ACA has actively supported the Office of the Prosecutor General in its efforts to investigate grave international crimes. This support ranges from general advice on the overall work organisation and the development of strategic approaches in similar proceedings, to the assessment of individual cases, preparation of legal analysis and collection of evidence on the ground. In practice, it was the ACA that was expected to assume coordination functions carried out by the public prosecutor's offices[520]. Specifically, the ACA facilitated the creation of a specialised unit for conflict-related sexual violence within the War Department of the OPG. The ACA's efforts, as highlighted in public statements by the OPG “have pioneered a unique model of international cooperation in the investigation of grave international crimes”[521].

While lack of the national authorities' capacity to investigate and prosecute such an immense number of alleged atrocity crimes generates a need for the international assistance, engagement and participation of international experts puts in jeopardy the integrity of the investigations and undermines the chances of successful prosecutions in courts at the domestic level. Incidentally, Ukraine’s legislation does not allow for retroactive application.

Therefore, even if the law was amended so as to grant a proper legal status to international experts, investigations, where there has already been such an interference, could still be considered as “contaminated”.

Separately, back in 2021, the OPG established the International Expert Council on Crimes Committed in the Context of the Armed Conflict[522]. It brings together national and international experts in international law, representatives of non-governmental organisations and journalists. However, it is difficult to fully assess the significance and outcomes of the Council’s work, given the ongoing discussions on various proposals and the ever-expanding scope of its topics[523]. However, when the Council examines various aspects of the investigation of grave international crimes, its thematic panels do not coordinate with each other, each promoting solutions in their designated thematic areas in silos.

For instance, one of the outputs of the CRSV sub working group was the draft Law of Ukraine ‘On Amendments to Criminal Procedure Code of Ukraine Regarding Improving the Procedure for Pre-trial Investigation and Trial in Criminal Proceedings on Crimes Related to Sexual Violence Committed in Context of Armed Conflict’ (Reg. No. 9351 dd. 05.06.2023[524]). The draft proposes amendments to the CPCU exclusively in the context of investigating conflict-related sexual violence. At the same time, the rules of criminal procedure require general amendments to facilitate the investigation of grave international crimes, which this draft does not address.

It is quite difficult to analyse the efforts of other states to investigate the consequences of the armed conflict in Ukraine after 24 February 2022 through the prism of the legislation.

1. While Ukrainian criminal procedure law defines the forms of international legal cooperation between states through bilateral and multilateral treaties, not all actions of states clearly fall within their scope. Firstly, Ukraine's national legislation refers to specific criminal proceedings within which international legal assistance can be provided. Given the number of proceedings related to the consequences of the armed conflict in Ukraine, it is difficult to determine which specific incident requires international assistance. Ultimately, from the common-sense perspective, all these proceedings require such assistance. 
2. Secondly, in order to receive international legal assistance, a state must make a formal request based on a treaty on legal assistance between states. Such a request should specify the scope of the assistance and detail the procedural actions required. 
3. Thirdly, according to the CPCU, foreign experts do not have a legal status in Ukraine and they cannot provide formal assistance in the domestic investigations. Instead, the framework of international legal assistance envisages their cooperation with the national authorities and participation in their activities within criminal proceedings[525].

Provided that Ukraine is a civil law system unless their status is defined in national legislation one cannot presume that these experts have an official role in criminal proceedings, as well as authority or legal capacity to undertake procedural actions. This creates a problem of admissibility of information obtained through the work of such experts. There is a risk that the evidence collected may not meet the criterion of legality. Considering that international experts assist in the investigation of specific criminal proceedings, there is also a challenge of granting them access to the case files as such actions may be perceived as breaching the confidentiality and integrity of the pre-trial investigation. The consequence of disregarding these rules may result in lost cases in courts due to the violations of procedure.

While Ukrainian justice system authorities welcome the assistance of foreign counterparts in the investigation of war crimes they cannot benefit from it without a proper legal basis. If international expert support is to be considered an effective form of collaboration with law enforcement agencies a relevant legislative framework must be created.