The request for an examination of the Rome Statute's constitutionality was made by the President of Ukraine pursuant to Article 151 of that country's constitution. The President contended that several provisions of the Rome Statute were not in conformity with the Ukrainian Constitution, in particular the provisions concerning the principle of complementarity, the irrelevance of official capacity, the transfer of Ukrainian citizens to the Court and the enforcement of sentences in third States. In contrast, the Ministry of Foreign Affairs argued that the Statute did not contradict the Constitution.
The Court concluded that most provisions of the Rome Statute were in conformity with the Constitution, except for paragraph 10 of the Preamble and Article 1, which states that the jurisdiction of the ICC "shall be complementary to national criminal jurisdictions". Under Article 9 of the Constitution, the conclusion of international treaties not in conformity with the Constitution can take place only after amendment of the Constitution.
Article 124 of the Ukrainian Constitution states that the administration of justice is the exclusive competence of the courts and that judicial functions cannot be delegated to other bodies or officials. The Constitutional Court noted that the jurisdiction of the ICC under the Rome Statute is complementary to national judicial systems. However, under Article 4(2) of the Rome Statute, the ICC may exercise its functions and powers on the territory of any State party, and under Article 17 , the ICC may find a case to be admissible if the State is unwilling or unable genuinely to carry out the investigation or prosecution. The Court concluded that jurisdiction supplementary to the national system was not contemplated by the Ukrainian Constitution. Hence, the amendment of the Constitution is required before the Statute can be ratified.
Article 125 of the Ukrainian Constitution prohibits the creation of "extraordinary and special courts". The Court held that, given that the Rome Statute was based on respect for individual rights and freedoms and included mechanisms to ensure impartial justice, the ICC could not be viewed as an "extraordinary or special court", the latter being national courts which replace ordinary courts and which do not apply established legal procedures.
The Court also held that the Rome Statute was not contrary to Article 121 of the Ukrainian Constitution, which entrusts the procuracy with prosecuting cases on behalf of the State, since that provision concerns only the prosecution of cases before the national courts. There was no need for constitutional amendment since the provisions of the Rome Statute on cooperation and assistance could be implemented through ordinary legislation.
The Ukrainian Constitution sets forth immunities from prosecution for the President, members of the Assembly and judges. The Court was of the opinion that Article 27 of the Rome Statute was not contrary to the immunities granted by the Constitution, since the crimes subject to the jurisdiction of the ICC were crimes under international law recognized by customary law or provided for in international treaties binding on Ukraine. The immunities granted by the Constitution were applicable only before national jurisdictions and did not constitute obstacles to the jurisdiction of the ICC.
Article 25 of the Ukrainian Constitution prohibits the surrender of nationals to another State. The Court noted that international practice distinguished between the extradition of a person to a State and the transfer of a person to an international tribunal. Article 25 prohibits only the surrender of a national to another State and is not applicable to a transfer to an international court, which could not be considered as a foreign court. The aim of the prohibition – the guarantee of a fair and unbiased trial – is met in the case of the ICC by means of the Statute's provisions, which are largely based on international human rights instruments and ensure a fair trial.
Lastly, the Court examined the possibility that Ukrainian citizens serving sentences in another State may enjoy fewer human rights guarantees than those provided by the Ukrainian Constitution. Article 65 of the Ukrainian Constitution states that "constitutional human and citizens' rights and freedoms shall not be restricted, except in cases envisaged by the Constitution of Ukraine." The Court was of the opinion that the risk of the rights and freedoms of Ukrainian citizens serving sentences in another State being more limited than those guaranteed by the Ukrainian Constitution could be diminished by means of a declaration stating Ukraine's willingness to have sentenced Ukrainian citizens serve their sentences in Ukraine. It also noted the criteria to be taken into account by the Court in designating the State of enforcement: the application of widely accepted international treaty standards governing the treatment of prisoners, and the views and the nationality of the sentenced person.