45. For the purposes of admissibility, the Commission must decide if the events can be characterized as a violation, as stipulated in Article 47(b) of the American Convention, or if the petition is “manifestly groundless” or “obviously out of order,” pursuant to subparagraph (c) of that Article. The standard for evaluating these requirements is different from that for deciding on the merits of a petition; the Commission must conduct a prima facie evaluation to determine whether the petition establishes grounds for the apparent or potential violation of a right guaranteed by the Convention, but not to establish the existence of a violation.8 This determination involves a summary analysis that does not imply a prejudgment on the substance of the matter. In establishing two stages, one involving admissibility and the other the merits, the Commission’s Rules of Procedure reflect this distinction.9 46. With respect to whether review of this petition would place the Commission in the position of acting as a “fourth instance” of review, the Commission’s case law clearly sets forth that it is “not competent to review judgments handed down by national courts acting within the scope of their jurisdiction and observing due judicial guarantees.” 10 The Commission “cannot serve as an appellate court to examine alleged errors of internal law or fact that may have been committed by the domestic courts acting within their jurisdiction.” 11 However, within its mandate to ensure the observance of the rights set forth in the Convention, the Commission is necessarily “competent to declare a petition admissible and rule on its merits when it portrays a claim that a domestic legal decision constitutes a disregard of the right to a fair trial,” or alleges other violations of rights protected thereunder 12--as is the case in the present petition. The State’s argument questioning whether the petitioners have presented sufficient elements of fact and law to support a violation of the right to life will be addressed in the merits stage of these proceedings. The Commission finds in the present case that the petitioners have stated claims concerning alleged violations of the right to life, and judicial protection and guarantees, which, if consistent with other requirements and shown to be true, could tend to establish the violation of rights protected under Articles 1, 4, 8 and 25 of the American Convention. V. CONCLUSIONS 47. The Commission concludes that it is competent to take cognizance of the instant case and that the petition is admissible, pursuant to Articles 46 and 47 of the American Convention. 48. Based on the factual and legal arguments set forth above, and without prejudging the merits of the case, THE INTER-AMERICAN COMMISSION ON HUMAN RIGHTS, DECIDES: 1. To declare the present case admissible with respect to the alleged violation of the rights recognized in Articles 4, 8, 25 and 1(1) of the American Convention. 2. To notify the parties of this decision. 3. To continue with the analysis of the merits of the case. 8 IACHR, Report Nº 128/01, Herrera and Vargas [“La Nación”], Costa Rica, case 12.367, December 3, 2001, para. 50. 9 Id. 10 See generally, IACHR, Report Nº 101/00, case 11.630, Arauz et al., Nicaragua, October 16, 2000, para. 56, citing IACHR, Report Nº 39/96, case 11.673, Marzioni, Argentina, October 15, 1996, paras. 50-51. 11 IACHR, Report Nº 7/01, case 11.716 Güelfi, Panama, February 23, 2001, para. 20, quoting Marzioni, supra, para. 51. 12 Id. 9