15 of the Commission’s Rules of Procedure refer to ‘exceptional circumstances’ to combine the treatment of admissibility with the debate on the merits of the case, and the Commission did not justify what these circumstances were, but merely alluded to abstract affirmations, without satisfying the basic requirement of reasonableness; (iii) the Commission never explained “the nature of the facts that were the object of the petition,” or which aspect of the electoral process was questioned, disregarding its obligation to provide satisfactory justification for its decisions; and (iv) the change in the juridical situation signified by the commencement of the electoral process and the alleged victim’s absence from it, should have led the Commission to verify whether the reasons for the petition existed or subsisted, and to proceed to close the case in keeping with Article 48(1)(a) and (c) of the Convention. 52. The Commission maintained, among other arguments, that: (i) it had not granted the State the opportunity to offer additional opinions or elements, because it considered that the exceptional circumstances stipulated in Article 37(3) of its Rules of Procedure had been met. In this regard, the Commission took into account the nature of the facts that were the purpose of the petition, which challenged an aspect of the electoral process that was being conducted at the time – the Mexican electoral calendar – and the interest in preserving the effectiveness of the eventual decision that the organs of the inter-American human rights system would take; based on the foregoing, it considered it essential to process the petition as rapidly as possible; (ii) when processing the petition, each party had ample possibility to submit its arguments on admissibility and merits, and the Commission had even granted the State extensions on two occasions; (iii) the Commission merely complied with its obligations under the Convention, its Statutes and its Rules of Procedure, which could not be a motive for a preliminary objection; and (iv) the joinder of the stages of admissibility and merits is a possibility established in the Commission’s Rules of Procedure; consequently, its application and interpretation is an attribute of the Commission; the Court itself has recognized “the independence of the Commission’s decision-making processes,” which it has described as “the result of a collective exercise of an autonomous nature,” executed in its capacity as a supervisory organ of the American Convention. Based on the above, the Commission asked the Court to reject this preliminary objection. 53. The representatives did not add any observations to those submitted by the Commission. 54. Article 37(3) of the Rules of Procedure of the Commission establishes that: “In exceptional circumstances, and after having requested information from the parties in keeping with the provisions of Article 30 of these Rules of Procedure, the Commission may open a case but defer its treatment of admissibility until the debate and decision on the merits. The case shall be opened by means of a written communication to both parties.” 55 The Court observes that this norm establishes a limited number of formal requirements regarding the opening of a case and the Commission’s authority to defer the treatment of admissibility until the debate and decision on merits. This provides the Commission with flexibility in that respect. The Court finds that the Commission has acted in exercise of its regulatory powers and that, irrespective of whether the Commission executed this optional joinder, according to the case file, the parties had the opportunity to submit their arguments on both the admissibility and the merits of the case, and the Commission examined them and ruled on them, so that no harm was produced to the right of defense. The State has not proved how the Commission’s actions have entailed an error that could have adversely affected its right to defense. Based on the above, the Court rejects this preliminary objection. *