4 nature), progressive development means that the States Parties have the specific and constant obligation to advance as rapidly and efficiently as possible towards the full realization of this right,17 subject to available resources, by legislation or other appropriate means. 18 In addition, there is an obligation of non-retrogression vis-a-vis the rights achieved.19 Consequently, the obligations of respect and guarantee established in the Convention, as well as the domestic legal effects (Articles 1(1) and 2 of the American Convention), are essential to achieve its effectiveness. 8. As the judgment indicates, in each case examined, it is necessary to determine which type of obligations are involved in relation to the right to social security.20 The Inter-American Court noted that this case did not relate to the obligations of progressive development derived from Article 26 of the American Convention, but rather to the failure to implement the right to a pension as an integral part of the right to social security of Mr. Muelle Flores owing to the failure to execute and comply with the judgments handed down in his favor in the domestic sphere in the context of the privatization of the State company following his retirement. 21 9. In addition, the judgment addresses relevant aspects of the issue of older persons as a group in a situation of special vulnerability in relation to the enjoyment of the social rights,22 as well as the particular impact – material and emotional – on older persons of the failure to execute domestic judgments that protect the right to social security. 23 The judgment Cf. UN, Committee on Economic, Social and Cultural Rights, General Comment No. 3: The Nature of States Parties’ Obligations (Art. 2, Para. 1, of the Covenant), December 14, 1990, UN Doc. E/1991/23, para. 9, and Committee on Economic, Social and Cultural Rights, General Comment No. 19, The right to social security (Article 9), February 4, 2008, paras. 40 and 41. 17 Article 26 of the Convention establishes: “Article 26. Progressive Development. The States Parties undertake to adopt measures, both internally and through international cooperation, especially those of an economic and technical nature, with a view to achieving progressively, subject to available resources, by legislation or other appropriate means, the full realization of the rights implicit in the economic, social, educational, scientific, and cultural standards set forth in the Charter of the Organization of American States as amended by the Protocol of Buenos Aires.” 18 Cf. Case of Acevedo Buendía et al. (“Discharged and Retired Employees of the Comptroller’s Office”) v. Peru. Preliminary objection, merits, reparations and costs. Judgment of July 1, 2009. Series C No. 198, paras. 102 and 103; and Case of Poblete Vilches et al. v. Chile. Merits, reparations and costs. Judgment of March 8, 2018. Series C No. 349, para. 104. See also: “Working Group to Examine the National Reports envisioned in the Protocol of San Salvador.” Initially, the Working Group prepared the document “Progress indicators for measuring rights under the Protocol of San Salvador,” OEA/Ser.L/XXV.2.1; GT/PSS/doc.2/11 rev.2, of December 16, 2011, based on the guidelines and criteria presented by the Inter-American Commission on Human Rights. Following consultations with the States and civil society, these were adopted by the Forty-second General Assembly held in Cochabamba, Bolivia in June 2012 (AG/RES. 2713 (XLII-O/12). On that occasion, the rights to social security, health and education were addressed. Subsequently, a second group of rights was addressed and the Working Group issued the “Progress indicators for measuring rights contemplated in the Protocol of San Salvador – second group of rights,” OEA/Ser.L/XXV.2.1 GT/PSS/doc.9/13, adopted by the OAS General Assembly in Resolution AG/RES. 2823 (XLIVO/14), at the second plenary session on June 4, 2014. Finally, in 2015, the Working Group combined the two groups of rights and published the document “Progress indicators for measuring rights contemplated in the Protocol of San Salvador,” OEA/Ser.D/XXVI.11 (2015). On that occasions, they addressed the right to work and trade union rights, the right to adequate food, a healthy environment, and the benefits of culture. Cf. UN, Committee on Economic, Social and Cultural Rights, General Comment No. 19, The right to social security (Art. 9 of the Covenant), February 4, 2008, para. 42. 19 Cf. Case of Muelle Flores v. Peru. Preliminary objections, merits, reparations and costs. Judgment of March 6, 2019. Series C No. 375, paras. 190, 191 and 202. 20 Mr. Muelle Flores acquired his right to a pension under a State-administered contribution regime; in other words, he acquired the right to receive a pension having made contributions for several years. The legitimacy of his incorporation into this regime was confirmed by the domestic courts. 21 Cf. Case of Muelle Flores v. Peru. Preliminary objections, merits, reparations and costs. Judgment of March 6, 2019. Series C No. 375, para. 207. 22 23 Cf. Case of Muelle Flores v. Peru. Preliminary objections, merits, reparations and costs. Judgment of March 6,