Norma relacionada
Practice Relating to Rule 20. Advance Warning
Spain’s LOAC Manual (1996) states: “Whenever circumstances permit, warning must be given of any attack that may affect the civilian population.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, División de Operaciones, 18 March 1996, Vol. I, § 2.3.b.(2); see also § 10.8.e.(2) and f.(1)
Spain’s LOAC Manual (2007) states that, during the execution phase of an attack: “Effective advance warning must be given of attacks that may affect the civilian population, if circumstances permit and the surprise factor is not essential to the success of the attack.” 
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, § 4.5.a.(1).(b); see also §§ 2.3.b.(2) , 2.4.c.(6) and 7.3.a.(1).
In 2010, in the Couso case, the Criminal Chamber of Spain’s Supreme Court was called upon to decide an appeal in the case concerning the killing of a Spanish journalist in Baghdad on 8 April 2003 by troops of the United States of America. In deciding upon one of the issues raised in the appeal on whether there was a breach of the law due to the failure to apply the national and international provisions on the principle of precaution, the Court held:
1. … There is no trace – as opposed to what is stated in the order – that there was a visual mistake concerning the presence of a sniper … in the hotel. … [There is also no evidence] that the [US] tank was fired upon in the 35 minutes prior [to the attack on the hotel] or that there was anti-vehicle artillery capable of reaching it from the hotel, taking into account that the tank was more than 1500 metres away and that an RPG grenade launcher does not reach more than 650 metres. Even if there had been such a risk, the journalists in the hotel should have been warned.
2. Due to their similarity with this matter, we must refer to what has been said in relation to the fifth and sixth issues raised by the previous appellants concerning the existence of rational indications of the commission of an offence which violate the ius in bello, namely the norms of International Humanitarian Law that must be observed by belligerents. 
Spain, Supreme Court, Couso case, Judgment, 13 July 2010, Section II(III), Octavo, §§ 1–2, p. 17; see also Section II(II), Sexto, § 2, p. 16.
[emphasis in original]
The Court upheld the appeal against the order of 23 October 2009 by the Third Section of the Criminal Chamber of the Spanish National Court, which declared the termination of the proceedings, and held that “the proceedings must continue, and the outstanding preparatory enquiries must be undertaken, as well as any others arising from the clarification of the events under investigation.” 
Spain, Supreme Court, Couso case, Judgment, 13 July 2010, Section III, pp. 20–21.