3 the absolute prohibition of torture arises from the supreme material source of law, the universal juridical conscience. The recognition and expansion of the sphere of international jus cogens also derives from the latter. 9. In this respect, in my Separate Opinion on the Inter-American Court’ Advisory Opinion No. 18 on The Juridical Status and Rights of Undocumented Migrants (of September 17, 2003), I indicated that: “(...) In the A. Furundzija case (Judgment of December 10, 1998) the International Criminal Tribunal for the former Yugoslavia (Trial Chamber) stated that the absolute prohibition of torture, decreed by international law – both treaty law (under various human rights treaties) and common law – had the character of a jus cogens norm (...). This was so owing to the importance of the values protected (...). This absolute prohibition of torture, the Tribunal added, imposed obligations erga omnes on States (...); the jus cogens character of this prohibition ‘makes it one of the most fundamental standards of the international community’, incorporating ‘an absolute value from which no one shall deviate’ (...). Indeed, the concept of jus cogens is not limited to treaty law; it belongs also to the law on the international responsibility of States. (...) In my opinion, it is in this pivotal chapter of international law, on international responsibility (perhaps more than in the chapter on treaty law), that jus cogens reveals its real, broad and profound dimension, covering all juridical acts (even unilateral ones) and (even beyond the sphere of State responsibility) influencing the very foundations of a truly universal international law” (paras. 69-70) 10. Today, there is a movement towards establishing a continuous monitoring mechanism of a preventive nature within the framework of the international juridical regime against torture. 6 Under the 1987 European Convention, the Committee for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment carries out preventive inspections in detention establishments in the States Parties (article 2). 7 In the same way, the recent Optional Protocol (2002) of the United Nations Convention against Torture authorizes the Sub-Committee on the Prevention of Torture (created by this Convention) to conduct preventive visits to detention establishments in the States Parties and make recommendations to them (articles 4 and 11). 11. These developments have ended one of the last remaining strongholds of State sovereignty, by allowing scrutiny of the sancta sanctorum of the State – including its prisons and detention establishments, police stations, military prisons, detention centers for foreigners, and psychiatric institutions – and of its administrative practices 6 Cf., see, in general, N.S. Rodley, The Treatment of Prisoners under International Law, Oxford, Clarendon Press, 1987, pp. 1-374; and cf. J. Donnelly, “The Emerging International Regime against Torture”, 33 Netherlands International Law Review (1986) pp. 1-23. 7 Cf. Council of Europe, Explanatory Report of the European Convention for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment, Strasbourg, C.E., 1989, pp. 5-23, esp. pp. 10-11 and 21; D. Rouget, "La Convention Européenne pour la Prévention de la Torture et des Peines ou Traitements Inhumains ou Dégradants - Un outil essentiel de promotion de la dignité des personnes privées de liberté", 2 Cahiers de l'Institut des Droits de l'Homme - De la prévention des traitements inhumains et dégradants en France - Lyon (1996) pp. 17-31; Comité Européen pour la Prévention de la Torture et des Peines ou Traitements Inhumains ou Dégradants, Contexte historique et principales caractéristiques de la Convention, Strasbourg, Conseil de l'Europe, [1991], pp. 1-4.