10 State’s declaration, during a working meeting held at the seat of the Commission on October 11, 2007, that it was unable to report on progress concerning the recommendations made by the Commission in Report on Admissibility and Merits No. 13/07 because it had been unable to establish contact with the authorities of the state of Paraná, allowed it to conclude that, as of that time, Brazil had violated Article 28 of the Convention. Accordingly, it asked the Court to reject the preliminary objection. * * * 34. The Court observes that the State’s allegation corresponds to a preliminary objection, designed to prevent the Court from examining the alleged non-compliance with Article 28 of the American Convention, containing the “federal clause.” 35. When the Commission’s actions in relation to the proceedings before it have been alleged as a preliminary objection, the Court has stated that the Inter-American Commission has autonomy and independence in the exercise of its mandate, as established by the American Convention16 and, in particular, in the exercise of its functions in relation to processing individual petitions, established by Articles 44 to 51 of the Convention.17 Nevertheless, when the Court is examining a case, it has the authority to control the legality of the measures taken by the Commission when processing the matter.18 The Court has upheld the opinion that the American Convention grants it full jurisdiction over all matters relating to a case submitted to its consideration, including those concerning the procedural assumptions on which its capacity to exercise its competence is founded.19 This does not necessarily entail reviewing the proceedings before the Commission, except in exceptional cases where a grave error exists that violates the right to defense of the parties.20 36. Moreover, the party that indicates that a grave error has occurred affecting its right to defense, owing to an action by the Commission during the proceedings before it, must prove this injustice.21 Hence, a complaint or difference of opinion with regard to the InterAmerican Commission’s actions is, in itself, insufficient. 37. The Court observes that the case file does not support the State’s argument that the alleged failure to comply with Article 28 was not considered during the proceedings before the Inter-American Commission and had only been included in the application after the State had made a comment during a working meeting on compliance with the reparations required in Report on Admissibility and Merits No. 13/07. During its proceedings, the Commission examined the facts of the case in light of Article 28 of the American 16 Cf. Control of the Legality of the Exercise of the Attributions of the Inter-American Commission on Human Rights (Arts. 41 and 44 to 51 of the American Convention on Human Rights). Advisory Opinion OC-19/05 of November 28, 2005. Series A No. 19, first operative paragraph; Case of Escher et al., supra note 9, para. 22, and Case of Castañeda Gutman, supra note 10, para. 40. 17 Cf. Control of the Legality of the Exercise of the Attributions of the Inter-American Commission on Human Rights (Arts. 41 and 44 to 51 of the American Convention on Human Rights), supra note 16, second operative paragraph; Case of Escher et al., supra note 9, para. 22, and Case of Castañeda Gutman, supra note 10, para. 40. 18 Cf. Control of the Legality of the Exercise of the Attributions of the Inter-American Commission on Human Rights (Arts. 41 and 44 to 51 of the American Convention on Human Rights), supra note 16, third operative paragraph; Case of Escher et al., supra note 9, para. 22, and Case of Castañeda Gutman, supra note 10, para. 40 19 Cf. Velásquez Rodríguez v. Honduras. Preliminary objections. Judgment of June 26, 1987. Series C No. 1, para. 29; Case of Escher et al., supra note 9, para. 22, and Case of Castañeda Gutman, supra note 10, para. 40. 20 Cf. The Dismissed Congressional Workers (Aguado Alfaro et al.) v. Peru, Preliminary objections, merits, reparations and costs. Judgment of November 24, 2006. Series C No. 158, para. 66; Case of Escher et al., supra note 9, para. 22, and Case of Castañeda Gutman, supra note 10, para. 40. 21 Cf. Case of the Dismissed Congressional Workers (Aguado Alfaro et al.), supra note 20, para. 66; Case of Escher et al., supra note 9, para. 23, and Case of Castañeda Gutman, supra note 10, para. 42.