8 Status and Rights of Undocumented Migrants (of 17.09.2003), I noted that said erga omnes obligations, characterized by jus cogens (from which they derive)8, being necessarily objective in nature, therefore encompass all the addressees of the legal provisions (omnes), both members of the bodies of the public State authorities and private individuals (para. 76). And I added: "In my view, we can consider such erga omnes obligations from two dimensions, one horizontal and the other vertical, which complement each other. Thus, the erga omnes obligations of protection, in a horizontal dimension, are obligations pertaining to the protection of human beings that pertain to the international community as a whole9. In the framework of international treaty law, they bind all the States Parties to human rights treaties (obligations erga omnes partes), and, in the ambit of general international law, they bind all the States that constitute the organized international community, whether or not they are Parties to those treaties (obligations erga omnes lato sensu). In a vertical dimension, the erga omnes obligations of protection bind both the bodies and agents of (State) public power, and the individuals themselves (in inter-individual relations). The advent and evolution of International Human Rights Law have decisively contributed to development of this vertical dimension. But it is surprising that, until now, these horizontal and vertical dimensions of the erga omnes obligations of protection have gone entirely unnoticed by contemporary legal doctrine. Nevertheless, I see them clearly take shape in the legal system of the American Convention on Human Rights itself. Thus, for example, as to the vertical dimension, the general obligation, set forth in Article 1(1) of the American Convention, to respect and to ensure respect for the free exercise of the rights protected by it, generates erga omnes effects, encompassing relations of the individual both with the public (State) authorities as well as with other individuals (particuliers).10” (paras. 77-78) 26. Actually, contemporary legal doctrine, addressing erga omnes obligations, has focused almost exclusively on the horizontal dimension, without establishing a distinction with regard to the other, vertical dimension, and without addressing the latter at all. The facts in the instant case of the Mapiripán Massacre have shown the urgent need to pay greater attention to what I call the vertical dimension of the erga omnes obligations to provide protection. 27. I have been insisting on this point –shown once again in the cas d'espèce – within . In this same Opinion, I noted that “By definition, all the norms of jus cogens necessarily generate obligations erga omnes. While jus cogens is a concept of material law, the erga omnes obligations refer to the structure of their performance on the part of all the entities and all the individuals bound by them. In turn, not all erga omnes obligations necessarily refer to norms of jus cogens.” (para. 80) 8 9 . IACtHR, Blake versus Guatemala case (Merits), Judgment of 24.01.1998, Separate Opinion of Judge A.A. Cançado Trindade, para. 26, and see paras. 27-30. 10 . See, in this regard, in general terms, the resolution adopted by the Institut de Droit International (I.D.I.) at the 1989 session in Santiago de Compostela (Article 1), in: I.D.I., 63 Annuaire de l'Institut de Droit International (1989)-II, pp. 286 and 288-289.