26. First, it appears from the case files that during the respective admissibility and merits proceedings in the instant case before the Commission, the State affirmed that the reforms of the Costa Rican Criminal Procedure System made it possible to adapt its domestic legal system to the provisions of Article 8(2)(h) of the American Convention, in compliance with the judgment in the case of Herrera Ulloa v. Costa Rica, 16 delivered by this Court on July 2, 2004. Consequently, the Court considers that the principle of estoppel is not applicable to the State. 17 27. Now, in the terms in which the present preliminary objection has been filed, this Court clarifies that, under Articles 67 and 68(1) of the American Convention, “[t]he judgment of the Court shall be final and not subject to appeal” and that “[t]he States Parties to the Convention undertake to comply with the decision of the Court in any case to which they are parties.” These treaty provisions, which derive from the basic principle of the international responsibility of States, constitute the main foundation that renders the judgments of this Court binding on the parties to an international dispute, along with the correlative duty to abide by and comply with everything established therein. 18 This absolute link between the contents and effects of the judgment and the parties to the dispute, which is where the authority of res judicata is created, corresponds to a principle of international law. 28. Article 47(d) 19 of the American Convention provides that a petition is inadmissible when it is substantially the same as a previous petition or communication already examined by the Commission or by another international body. In this regard, the Court has established that the phrase “substantially the same” means that there must be “identity” or similarities between the cases. In order for this identity to exist, three elements must be present, namely: the parties must be the same, the subject matter must be the same and the legal grounds must be identical. 20 However, it should be noted that the State is not alleging the identity of these three elements with respect to the whole of this case with the Herrera Ulloa case, but rather with respect to the alleged violation of the right to appeal the judgment. 29. In this regard, it is evident that, both in the Herrera Ulloa case and in the instant case, part of the legal basis is identical with respect to the alleged violation of the right to appeal During the admissibility proceeding for the eight initial petitions, the State informed the Commission that it had adopted Laws 8503, 8837 and their respective transitional provisions I and III, and argued that “by decision of the Inter-American Court of November 22, 2010 concerning monitoring compliance with the judgment in the case of Herrera Ulloa, the Court concluded the case, in light of the aforementioned law, and ordered it archived, finding that Costa Rica had fully complied with the decision in that judgment. Therefore, it contends that the InterAmerican Court found that Costa Rica gave effect to the provisions of Article 8 (2) (h) of the American Convention, ensuring comprehensive supervision or enforcement of the decisions of the trial courts.” Cf. Admissibility Report 105/11 of July 22, 2011 (evidence file, folios 18246). 17 The Court has indicated that when a party in a case adopts a position that is either beneficial to it or detrimental to the other party, the principle of estoppel prevents it from subsequently assuming the contrary position. Cf. Case of Neira Alegría et al. v. Peru. Preliminary objections. Judgment of December 11, 1991. Series C No. 13, para. 29, and Case of the Garífuna Community of Triunfo de la Cruz and its members v. Honduras. Merits, reparations and costs. Judgment of October 8, 2015. Series C No. 305, Para. 22. 18 The Court reiterates that the obligation to comply with the judgments of this Court is a basic principle of international law, supported by international jurisprudence, according to which States must fulfill all their international treaty obligations in good faith (pacta sunt servanda); and, as already noted by this Court and established in Article 27 of the 1969 Vienna Convention on the Law of Treaties, domestic law may not be invoked as justification for failure to observe international obligations. Cf. International responsibility for the promulgation and enforcement of laws in violation of the Convention (Arts. 1 and 2 of the American Convention on Human Rights), Advisory Opinion OC-14/94 of December 9, 1994. Series A No. 14, para. 35. 19 Article 47(d) of the American Convention establishes that: “The Commission shall consider inadmissible any petition or communication submitted under Articles 44 or 45 if: […] d) the petition or communication is substantially the same as one previously studied by the Commission or by another international organization.” 20 Cf. Case of Baena Ricardo et al. v. Panama. Preliminary objections. Judgment of November 18, 1999. Series C No. 61, para. 53, and Case J. v. Peru. Preliminary objection, merits, reparations and costs. Judgment of November 27, 2013. Series C No. 275, Para. 30. 16 13