9 supported by international case law, according to which a State must fulfill its international treaty obligations in good faith (pacta sunt servanda) and, as this Court has already indicated, and as established in Article 27 of the 1969 Vienna Convention on the Law of Treaties, a party may not invoke the provisions of its internal law as justification for its failure to perform a treaty.2 The treaty obligations of the States Parties are binding for all the powers and organs of the State. 6. That the States Parties to the Convention must ensure compliance with its provisions and their inherent effects (effet utile) within their respective domestic legal databases. This principle is applicable with regard not only to the substantive norms of human rights treaties (that is, those which contain provisions on the protected rights), but also with regard to the procedural norms, such as those referring to compliance with the decisions of the Court. These obligations shall be interpreted and applied so that the guarantee protected is truly practical and effective, bearing in mind the special nature of human rights treaties.3 7. That the States Parties to the Convention that have accepted the compulsory jurisdiction of the Court have the duty to comply with the obligations established by the Court. These obligations include the State’s duty to report to the Court on the measures adopted to comply with the measures ordered by the Court in its decisions. The opportune observance of the State’s obligation to report to the Court on how it is complying with each of the elements ordered by the Court is fundamental for assessing the status of compliance with the Judgment as a whole.4 * * * 8. That, when monitoring full compliance with the Judgment on merits, reparations, and costs in this case, and after examining the information provided by the State, the Inter-American Commission, and the representatives of the victims and their next of kin in their respective briefs on compliance with the reparations (supra Having seen paragraphs 5 to 7), the Court has determined which of the decisions in the Judgment that have been complied with either completely or partially by El Salvador, and also the reparations that remain pending. The Court appreciates the fact that the State has submitted information on all the reparations it ordered. 9. That the Court has verified that El Salvador has complied with: (a) “Designation of a day dedicated to the children disappeared during the internal armed conflict for different reasons” (tenth operative paragraph of the Judgment of March 1, 2005). The State has declared March 29 every year as the 2 Cf. Case of the Sawhoyamaxa Indigenous Community. Compliance with Judgment, supra note 1, third Considering paragraph; Case of Yatama. Compliance with Judgment supra note 1, fifth Considering paragraph; and Case of Cesti Hurtado, Compliance with Judgment, supra note 1, seventh Considering paragraph. 3 Cf. Case of the Sawhoyamaxa Indigenous Community. Compliance with Judgment, supra note 1, fourth Considering paragraph; Case of Yatama. Compliance with Judgment, supra note 1, sixth Considering paragraph; and Case of Cesti Hurtado, Compliance with Judgment supra note 1, eighth Considering paragraph. 4 OAS General Assembly, Resolution AG/RES. 2292 (XXXVII-O/07) adopted at the fourth plenary session held on June 5, 2007, entitled: “Observations and Recommendations on the Annual Report of the Inter-American Court of Human Rights.”