appeal for amparo was suitable and effective to dispute the decision taken by the CNM, a matter that is also related to the Merits of this dispute. 35. Similarly, the State requested that a review of legality be made of the actions of the InterAmerican Commission in relation to the lack of exhaustion of domestic remedies, with regard to the normative framework applied. The Court recalls that, in matters brought to its attention, it has the power to review the legality of the Commission's actions. However, this does not necessarily imply an ex officio review of the procedure that was carried out in that instance. In addition, the Court must maintain a fair balance between the protection of human rights, the ultimate goal of the Inter-American System, and the legal security and procedural fairness that ensure the stability and reliability of international protection. The review indicated may proceed, then, in those cases in which one of the parties alleges that there is a serious error that violates their right of defense, in which case they must effectively demonstrate such harm. A complaint or discrepancy of criteria in relation to the actions of the Inter-American Commission is not sufficient. 25 36. In this case, Peru alleged that Messrs. Cuya Lavy, Valenzuela Cerna, and Díaz Alvarado, and Ms. Rodríguez Ricse had not alleged, in domestic jurisdiction or before the Commission, the violation of the principle of legality, so it did not have the opportunity to file the preliminary objection of the lack of exhaustion of domestic remedies in relation to this matter, at the appropriate procedural moment. In this regard, the Court finds that the litigation in this case has been related from the beginning to the process that gave rise to the alleged victims' nonratification in office, and this necessarily includes the normative framework applied and the possible violations to the principle of legality due to the lack of classification of the causes that gave rise to the non-ratification. Thus, the State has had knowledge of the subject matter of the dispute since then and could have presented arguments on this point or a preliminary objection at the appropriate procedural moment. 37. Consequently, the Court concludes that both the request for review of legality and the preliminary objection of failure to exhaust domestic remedies are not admissible. B. Exception on the alleged lack of jurisdiction of the Court to act as fourth instance B.1. Arguments of the State and observations of the Commission and the representatives 38. The State argued that the Commission has acted as a court of fourth instance and its role is not to act as a substitute for the national jurisdictional authorities in interpreting the substantive and procedural norms applicable to cases. However, it also stated that it is not unaware that the Commission or the Court can carry out the review of internal processes as long as there are violations of human rights recognized in the American Convention. Regarding Mr. Cuya Lavy and Mr. Valenzuela Cerna, Peru alleged that, in the Final Report, the Commission questioned the reasoning of the order that decided not to ratify them and its connection with the principle of legality, despite the fact that this allegation was not raised domestically. Regarding the alleged victims Díaz Alvarado and Rodríguez Ricse, the State declared that their proceedings were submitted after the deadline and therefore there was not actually an exhaustion of remedies and, nevertheless, the Commission questions the violation of rights at a supranational level. The State concluded that the Commission acted as an appellate court by classifying, in its Merits Report, aspects that were not exhausted at the domestic level. 25 Cf. Case of the Saramaka People v. Suriname. Preliminary Objections, Merits, Reparations and Costs. Judgment of November 28, 2007. Series C No. 172, para. 32, and Case of Urrutia Laubreaux v. Chile. Preliminary Objections, Merits, Reparations and Costs. Judgment of August 27, 2020. Series C No. 409, para. 25. 12