Related Rule
Spain
Practice Relating to Rule 161. International Cooperation in Criminal Proceedings
Section E. Cooperation with international criminal tribunals
Spain’s LOAC Manual (1996) states:
Historically … International Tribunals established to judge alleged war criminals have existed (such as the Nuremberg and Tokyo Tribunals), and this possibility remains nowadays and seems to be a developing trend for the action of the International Community, an example of which is the creation by the Security Council of … [the International Criminal Tribunal for the former Yugoslavia]. To cooperate with [this Tribunal], Spain has adopted Organic Law No. 15/94 of 1 June. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, § 7.6.b.(2).
The manual further states:
The obligation devolving on the States to cooperate in the penal repression of grave breaches of the [1949 Geneva] Conventions is not limited to cooperation with other States but also comprises cooperation with the United Nations, in conformity with the United Nations Charter. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, § 11.8.b.(5).
Spain’s LOAC Manual (2007) states: “Spain is party to the Rome Statute and has enacted organic law 18/2003 governing cooperation with the International Criminal Court.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 7.6.b.(2).
Spain’s Law on Cooperation with the ICTY (1994) states:
Spain will provide full cooperation to the International Tribunal for the Prosecution of Persons Responsible for Serious Violations of International Humanitarian Law Committed in the Territory of the Former Yugoslavia (hereinafter “International Tribunal”) established by Resolution 827 (1993) of the Security Council of the United Nations. 
Spain, Law on Cooperation with the ICTY, 1994, Article 1.
Upon ratification of the 1998 ICC Statute, Spain stated:
In relation to article 87, paragraph 1, of the [1998 ICC] Statute, the Kingdom of Spain declares that, without prejudice to the fields of competence of the Ministry of Foreign Affairs, the Ministry of Justice shall be the competent authority to transmit requests for cooperation made by the Court or addressed to the Court.
In relation to article 87, paragraph 2, of the [1998 ICC] Statute, the Kingdom of Spain declares that requests for cooperation addressed to it by the Court and any supporting documents must be in Spanish or accompanied by a translation into Spanish. 
Spain, Declarations made upon ratification of the 1998 ICC Statute, 24 October 2000.