Rule 161. States must make every effort to cooperate, to the extent possible, with each other in order to facilitate the investigation of war crimes and the prosecution of the suspects.
State practice establishes this rule as a norm of customary international law applicable in relation to war crimes committed in both international and non-international armed conflicts.
Additional Protocol I and the Second Protocol to the Hague Convention for the Protection of Cultural Property provide that parties to a conflict shall afford to one another the greatest measure of assistance in connection with investigations and criminal proceedings, including extradition, brought in respect of the war crimes listed in those treaties.
Similar provisions are to be found in the European Convention on Mutual Assistance in Criminal Matters, the OAU Convention against Mercenarism, the UN Mercenary Convention and the United States–Soviet Memorandum of Understanding on the Pursuit of Nazi War Criminals.
In 1989, the UN Security Council urged States to cooperate with each other in the context of the prohibition of hostage-taking,
and in 1998 it urged States to cooperate with the governments of the Democratic Republic of the Congo and Rwanda in the investigation and prosecution of those guilty of violations of international humanitarian law.
The UN General Assembly adopted several resolutions between 1970 and 1973 calling on States to cooperate in the investigation and prosecution of suspected war criminals.
It should be noted that these UN General Assembly resolutions attracted substantial numbers of abstentions, mainly, however, because the crimes covered by those resolutions were not clearly defined.
In two resolutions adopted unanimously and without a vote respectively, the UN Commission on Human Rights also urged States to take necessary measures to cooperate in order to ensure the prosecution of persons guilty of war crimes and crimes against humanity.
The voting record of the General Assembly resolutions, together with the fact that the UN Security Council and UN Commission on Human Rights urged
States to cooperate rather than calling on them to do so, indicates that there does not seem to be, in customary international law, an absolute obligation to cooperate, but rather an expectation that States should make efforts in good faith to do so, to the extent possible. It is significant that the United States, which is not party to Additional Protocol I, stated in 1987 that it supported the principle that appropriate authorities “make good faith efforts to cooperate with one another”.
There appears to be, therefore, general acceptance of the principle that States must make every effort to cooperate with each other, to the extent possible, in order to facilitate the investigation and trial of suspected war criminals and, in this regard, no distinction has been made by States between war crimes committed in international armed conflicts and war crimes committed in non-international armed conflicts. The forms of cooperation mentioned in the various resolutions include investigations, exchange of documents, arrest, prosecution and extradition.
There is uniformity of practice, both in treaty law and national law, to the effect that war crimes are subject to extradition under extradition treaties. However, there does not appear to be an obligation
to extradite persons suspected of war crimes. Additional Protocol I states that “when circumstances permit, [States] shall co-operate in the matter of extradition”. It adds that they “shall give due consideration to the request of the State in whose territory the alleged offence has occurred”.
All extradition agreements include conditions required for extradition (typically, the offence has to be a crime in both States with a minimum punishment provided for) and it should also be noted that it would be a violation of international law to extradite a suspect to a country where the person risks being subjected to torture or cruel or inhuman treatment or punishment. While there are examples of extraditions, such as in the Priebke case
in 1995 and the Cavallo case
in 2001, there have also been instances of refusal to extradite, inter alia
, because of the absence of an extradition treaty with the requesting State, such as the Barbie extradition case
A number of States specifically provide that they will not extradite their own nationals.
Many bilateral and regional extradition treaties, as well as national legislation, specify that there cannot be extradition for “political offences” but that this exception cannot apply to crimes under international law.
This principle is also set forth in other treaties.
It has been applied in national case-law.
This practice appears to show that cooperation in prosecuting suspected war criminals should include extradition when requested, but potentially subject to conditions. There is no indication that this rule is considered any differently for crimes committed in the context of international or non-international armed conflicts. If extradition is refused, then, in the case of grave breaches or other crimes where multilateral treaties provide for an obligation to try or extradite on the basis of universal jurisdiction, the requested State is required to try the alleged criminal itself. In case of other war crimes, the State is required to proceed with investigation and prosecution in accordance with Rule 158.
There are specific provisions for cooperation in the context of the statutes of international tribunals. Such cooperation must be undertaken either by virtue of the treaty, as in the case of the Statute of the International Criminal Court, or in order to implement binding UN Security Council resolutions, as in the case of the tribunals set up under Chapter VII of the Charter of the United Nations.