Norma relacionada
Practice Relating to Rule 140. The Principle of Reciprocity
Spain’s LOAC Manual (1996) notes: “International treaties and agreements are made up of imperative norms of law … They do not lose their validity because one of the opposing parties does not respect them.” 
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, § 1.1.d.(2).
Spain’s LOAC Manual (2007) states:
International treaties and conventions lay down peremptory norms from which no derogation is permitted, unless the treaty or convention in question provides for exceptions. Furthermore, the binding force of a treaty is not lessened by the failure of one of the parties to comply with it or by widespread or repeated non-compliance. 
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, § 1.1.d.(2).