Article 27 of the Vienna Convention on the Law of Treaties, 1969. 14. The above precedent was reiterated, with some variations, two months later in the Case of the Dismissed Congressional Employees (Aguado - Alfaro et al.) v. Peru. 15 In this ruling, the criterion applied in the Case of Almonacid Arellano regarding “conventionality control” is invoked and is “specified” in two ways: (i) it should be applied “ex officio,” without the parties requesting it; and (ii) judges should exercise it in the context of their respective spheres of competence and the corresponding procedural regulations, considering other formal and material assumptions on admissibility and appropriateness. 15. Since then, the essence of this doctrine has been gradually consolidated, in its application to the following contentious cases: La Cantuta v. Peru (2006); 16 Boyce et al. v. Barbados (2007); 17 Heliodoro Portugal v. Panama (2008); 18 Rosendo Radilla Pacheco v. the United Mexican States (2009); 19 Manuel Cepeda Vargas v. Colombia (2010); 20 The Xákmok Kásek Indigenous Community v. Paraguay (2010); 21 Fernández Ortega et al. v. Mexico (2010); 22 Rosendo Cantú et al. v. Mexico (2010); 23 Ibsen Cárdenas and Ibsen Peña v. Bolivia (2010); 24 Vélez 15 Case of Dismissed Congressional Employees (Aguado Alfaro et al.) v. Peru. Preliminary Objections, Merits, Reparations and Costs. Judgment of November 24, 2006. Series C No. 158, para. 128: When a State has ratified an international treaty such as the American Convention, the judges are also subject to it; this requires them to ensure that the effet util of the Convention is not reduced or annulled by the application of laws contrary to its provisions, object and purpose. In other words, the Judicial bodies should exercise not only constitutionality control, but also “conventionality control”15 ex officio between domestic norms and the American Convention; obviously within the framework of their respective competences and the corresponding procedural rules. This function should not be limited exclusively to the statements or actions of the plaintiffs in each specific case, nor should it imply that this control must always be exercised, without considering other procedural and substantive criteria regarding the admissibility and legitimacy of such actions. (underlining added). 16 Case of La Cantúta v. Peru. Merits, Reparations and Costs. Judgment of November 29, 2006. Series C No. 162, para. 173. 17 Case of Boyce et al. v. Barbados. Preliminary Objection, Merits, Reparations and Costs. Judgment of November 20, 2007. Series C No. 169, para. 79. 18 Case of Heliodoro Portugal v. Panama. Preliminary Objections, Merits, Reparations and Costs. Judgment of August 12, 2008. Series C No. 186, para. 180. 19 Case of Rosendo Radilla Pacheco v. United Mexican States. Preliminary Objections, Merits, Reparations and Costs. Judgment of November 23, 2009. Series C No. 209, para. 339. 20 Case of Manuel Cepeda Vargas v. Colombia. Preliminary Objections, Merits and Reparations. Judgment of May 26, 2010. Series C No. 213, para. 208, note 307. 21 Xákmok Kásek Indigenous Community v. Paraguay. Merits, Reparations and Costs. Judgment of August 24, 2010. Series C No. 214, para. 311. 22 Case of Fernández Ortega et al. v. Mexico. Preliminary Objection, Merits, Reparations and Costs. Judgment of August 30, 2010. Series C No. 215, para. 234. 23 Case of Rosendo Cantú et al. v. Mexico. Preliminary Objection, Merits, Reparations and Costs. Judgment of August 31, 2010. Series C No. 216, para. 219. 24 Case of Ibsen Cárdenas and Ibsen Peña v. Bolivia. Merits, Reparations and Costs. Judgment of September 1, 2010. Series C No. 217, para. 202. 6