Related Rule
Ukraine
Practice Relating to Rule 161. International Cooperation in Criminal Proceedings
Ukraine’s IHL Manual (2004) states:
In case of serious violations of international humanitarian law, parties to the armed conflict shall take measures individually and jointly, as well as in cooperation with the United Nations according to the Charter of the United Nations. 
Ukraine, Manual on the Application of IHL Rules, Ministry of Defence, 11 September 2004, § 1.8.9.
Ukraine’s IHL Manual (2004) states:
Each State shall be under the obligation to search for persons who have committed, or to have ordered to be committed, war crimes (including those crimes that were a result of a failure to take precautionary measures that had to be taken).
Any person charged with such crimes shall be handed over to a requesting State unless that person was brought to justice for serious violations of international humanitarian law in its own State. 
Ukraine, Manual on the Application of IHL Rules, Ministry of Defence, 11 September 2004, § 1.8.9.
In the Rome Statute case in 2001, the President of Ukraine made a submission to the Constitutional Court of Ukraine claiming that certain provisions of the 1998 ICC Statute were not in conformity with the Ukrainian Constitution. With regard to the legality of surrendering Ukrainian nationals to the ICC, the Constitutional Court stated:
2.3. Pursuant to part two of Article 25 of Ukraine’s Constitution, a citizen of Ukraine may not be extradited to another state.
Item 1 of Article 89 of the [1998 ICC] Statute stipulates that the International Criminal Court may submit a request for arrest and transfer of a person together with corresponding materials to any state on which territory the person stays, and address this state with a request for cooperation in arrest and transfer. Participating states, according to procedure stipulated by their national legislation, execute such a request.
[The President of Ukraine] considers that this provision of the Statute contradicts the aforementioned provision of Article 25 of Ukraine’s Constitution.
In his opinion, item 3 of Article 107 of the Statute does not comply with either, as the state enforcing a sentence may, pursuant to its legislation, extradite or otherwise surrender the person into the jurisdiction of a state which addressed it with a request to extradite or to surrender this person with the purpose of judicial prosecution or execution of sentence.
Analysis of provisions of Ukraine’s Constitution, the Statute and other materials of the case, as well as familiarization with special literature and international legal practice, provide grounds for Ukraine’s Constitutional Court to ascertain:
2.3.1. Terms “extradite” and “surrender” in general understanding of their application are considered often as synonyms, but in international legal documents and special literature they are understood with different sense of meaning, thus making their legal nature not identical.
Therefore, the international legal documents and special literature consider that delivery of a person to another equally sovereign state differs in principle from delivery of a person to the Court, established pursuant to international law with participation and agreement of interested states.
The first one is referred to in international legal terminology by the term “extradition” (from latin, ex: from, beyond; tradition: to transfer), and the letter by the term “surrender”.
The Statute also complies with this international legal practice, pursuant to its Article 102, “surrender” signifies the delivery of a person by a state to the Court, while “extradition” means the delivery of a person of one state to another state pursuant to provisions of international agreement, convention or national legislation.
2.3.2. According to part two of Article 25 of Ukraine’s Constitution, the extradition of Ukraine’s citizens to another state is prohibited. Therefore this prohibition concerns only national and not international jurisdiction. It aims to guarantee unbiased judicial review and justice and lawfulness of punishment for its citizens.
The International Criminal Court cannot be equated to a foreign court, as it is established, as stated before, with the participation and by agreement of participating states on the basis of international, not national law.
The purpose behind the prohibition to extradite citizens of one state to another is fulfilled in the International Criminal Court by applying the relevant provisions of the Statute that have been developed (or agreed) by the participating states. These provisions are based on international human rights treaties, by which Ukraine has already agreed to be bound.
2.3.3. Therefore the constitutional provisions related to the prohibition on extradition of citizens of Ukraine (even in case of a wide interpretation of the term “extradition”) should not be considered separately from the international and legal obligations of Ukraine.
Thus, it is necessary to consider the complementarity principle, stated in the Statute (Article 17), which stipulates that if national jurisdiction is being exercised with regard to persons who are guilty of committing the most serious international crimes, then the International Criminal Court should not exercise to them its own jurisdiction, therefore, the issue will not arise of their transfer to the International Criminal Court. 
Ukraine, Constitutional Court, Opinion of the Constitutional Court of Ukraine in the case of the constitutional submission by the President of Ukraine on issuing opinion related to compliance of the Rome Statute of the International Criminal Court to the Constitution of Ukraine, Case No 1-35/2001, 11 July 2001, §§ 2.3–3.3.