With Russia's full-scale invasion on 24 February 2022, Ukraine entered a new phase of the war, in which mass violations of international humanitarian law became not an exception but a systematic tactic of the aggressor. The killing of civilians, torture, the forced deportation of children, and the destruction of civilian infrastructure are merely the tip of the iceberg of crimes that demand not only documentation but also legal qualification and the punishment of those responsible. In this context, the International Criminal Court (hereinafter — the ICC) in The Hague was transformed from a distant institution, which the Ukrainian public perceived as a symbolic instrument of global justice, into a practical platform on which a precedent of international accountability for crimes of aggression is being formed. Ukraine's cooperation with the ICC has become a test of the national legal system's ability to integrate into the global mechanism of criminal prosecution, to preserve the sovereignty of investigation, and at the same time to supplement international proceedings with unique evidence that might otherwise be lost in the chaos of war.
Historically, Ukraine signed the Rome Statute of the ICC back in 2000, yet the path to its full ratification took more than two decades. This situation created a certain duality of status: Ukraine recognized the jurisdiction of the Court through special declarations (in 2014 and 2015) and had obligations regarding cooperation, but for a long time it remained deprived of the rights of a full-fledged member (for example, the right to vote in the Assembly of States Parties or the right to nominate its own candidates for judicial posts). The full-scale war became a catalyst for change. The ratification of the Statute in 2024 and the acquisition of full membership as of 1 January 2025 brought the period of legal uncertainty to an end. Now interaction with the ICC has moved to a new level: national authorities act not only as a source of evidence but as full-fledged participants in the international justice system. This demands of officials a high level of professional competence and strict adherence to standards of integrity in the collection and processing of information that is significant for the international criminal process.
The scale of Russian aggression has become an unprecedented challenge for the national system of law and order, since the prosecution bodies, which had traditionally specialized in ordinary criminality, suddenly faced the need to investigate an array of international crimes. This required fundamentally new expertise: deep knowledge of international humanitarian law, skills in working with aerospace imagery, digital forensics, and OSINT-intelligence tools. A strategically important step was the strengthening of the Department for Combating Crimes Committed in Conditions of Armed Conflict within the Office of the Prosecutor General; however, the practical implementation of this reform proved to be a complex task. The system felt an acute need for personnel who command English for direct interaction with international partners, who understand the architecture of the ICC, and who are capable of managing investigations spanning tens of thousands of episodes.
The first months of the full-scale war demonstrated that the mechanical recording of facts customary in national practice does not always meet the rigorous standards of admissibility of evidence in the Hague court. A fundamental transformation of the entire approach was required — from a simple description of events to the purposeful construction of evidentiary chains and adherence to the principle of chain of custody . An important element of this new model became the work within the Joint Investigation Team (JIT), created with the support of Eurojust, where Ukrainian law enforcement officers work shoulder to shoulder with colleagues from Poland, Lithuania, and other partner countries. This experience compelled national authorities to act as equal participants in the international criminal process, in which professional ethics, digital literacy, and institutional integrity became key conditions for ensuring the inevitability of punishment for the gravest crimes.
A key challenge has been the harmonization of two parallel processes: national criminal prosecution under Article 438 of the Criminal Code of Ukraine (violation of the laws and customs of war) and the investigation of the International Criminal Court. Interaction with the ICC is based on the principle of complementarity: national jurisdiction is the priority, and the ICC comes into operation only when a state is unwilling or genuinely unable to administer justice properly. This norm creates a constructive tension: Ukraine seeks to preserve the sovereign right to try war criminals, but at the same time it must prove to the international community that its legal system meets the highest standards of fair and impartial justice.
An important aspect of this interaction is the conformity of punishments with international norms. The previously widespread assertion of the existence of the death penalty in Ukrainian legislation is mistaken — Ukraine fully abolished this type of punishment back in 2000, which removed the key legal barriers to cooperation with European and international institutions. Instead, a pressing challenge remains the implementation of the norms of the Rome Statute into the national Criminal Code, in particular with regard to the clear definition of crimes against humanity and command responsibility. This requires not only political will but also a profound transformation of the legal consciousness of public officials and judges, since national verdicts must be impeccable from the standpoint of international law in order not to be challenged in the future.
The body of evidence formed in cooperation with the ICC differs fundamentally from traditional Ukrainian forensic practice. The Hague court requires strict adherence to the chain of custody, in which every stage — from the initial seizure at the crime scene to presentation in the courtroom — is documented so as to completely exclude any doubts about the authenticity of the data. Satellite images, drone recordings, and victim testimony must comply with international protocols, in particular the Istanbul Protocol on the documentation of traces of torture, in order to minimize the re-traumatization of victims and ensure the admissibility of evidence.
Ukraine has not only built the necessary infrastructure — from digital laboratories to platforms protected on the basis of blockchain technology — but has also turned into a global exporter of unique know-how in the field of documenting war crimes in the digital age. Now interaction with the ICC demands of officials not only technical knowledge but also impeccable professional ethics and institutional integrity, which is the guarantee of recognition of Ukraine's efforts at the international level.
Cooperation with the International Criminal Court has become for Ukraine not only a strategic instrument for bringing the guilty to account but also a powerful catalyst for reforming the national system of criminal justice. The ICC's high demands for the quality of evidence, the unswerving observance of procedural guarantees, and the protection of victims' rights establish new professional benchmarks for Ukrainian investigators and prosecutors. Every investigation conducted according to international standards is a substantial contribution to Ukraine's legal integration into the European space and to strengthening trust in its institutions.
At the same time, this interaction has the character of a mutually beneficial partnership: Ukraine affords the ICC a unique opportunity to demonstrate the effectiveness of international justice in conditions of active armed conflict, which is critically important for restoring the Court's authority on the global stage. The success of this synergy will determine not only the inevitability of punishment for the crimes of Russian aggression but also the viability of the entire system of international law and its capacity to counter the challenges of the twenty-first century effectively. In this context, the professional competence and ethical resilience of every public official become the foundation on which the international recognition of Ukraine's legal authority is built.
