Соответствующая норма
Spain
Practice Relating to Rule 101. The Principle of Legality
Spain’s LOAC Manual (1996) provides:
No prisoner shall be subject to judicial proceedings or be sentenced for an act which was not previously prohibited whether by the national legislation of the party under whose power he is, or by International Law in force at the time the act was committed. 
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, § 8.7.c.(1).
Spain’s LOAC Manual (2007) states: “No prisoner of war may be tried or sentenced for an act which is not forbidden by the law of the detaining power or by international law in force at the time the act was committed.” 
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, § 8.7.c.(1).
Spain’s Penal Code (1995), as amended in 2010, which includes a chapter on offences against protected persons and objects in the event of armed conflict, states:
The offences and faults committed up until the day of the entry into force of this Law will be judged according to the criminal legislation in force at the time of their commission. However, this Law will be applicable once it enters into force, as long as its provisions are more favorable to the prisoner, even if the facts occurred prior to its entry into force. 
Spain, Penal Code, 1995, as amended on 23 June 2010, Disposición transitoria primera (1), p. 54878.