3 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.3 5. The States Parties to the Convention must ensure compliance with its provisions and their inherent effects (effet utile) within their respective domestic legal systems. This principle is applicable not only with regard to the substantive norms of human rights treaties (that is, those which contain provisions concerning the protected rights), but also with regard to procedural norms, such as those referring to compliance with the decisions of the Court. These obligations shall be interpreted and applied so that the protected guarantee is truly practical and effective, bearing in mind the special nature of human rights treaties.4 6. The States Parties to the Convention that have accepted the Court’s compulsory jurisdiction have the duty to comply with the obligations established by the Court. This obligation includes the State’s duty to inform the Court about the measures it has taken to comply with the rulings of the Court in its decisions. The State’s prompt observance of its obligation to inform the Court about how it is complying with each of the aspects ordered by the Court is fundamental for evaluating the status of compliance with the judgment as a whole.5 a) Obligation to adopt available measures to determine the whereabouts of Ernesto Rafael Castillo Páez (second operative paragraph of the judgment on reparations) 7. After examining the documents forwarded by the State (supra fourth having seen paragraph), the Court found that they constitute “procedural documents from the [criminal proceedings] against Juan Carlos Mejía León and others for the crime against humanity - forced disappearance of Ernesto Castillo Páez […],”6 which the Court had already analyzed7 in its Order of April 3, 2009 (supra second having seen paragraph). In this Order, the Court indicated, inter alia: 2 Cf. International Responsibility for the Promulgation and Enforcement of Laws in Violation of the Convention (Arts. 1 and 2 American Convention on Human Rights). Advisory Opinion OC-14/94 of December 9, 1994. Series A No. 14, para. 35; Case of the Miguel Castro Castro Prison v. Peru. Monitoring compliance with judgment. Order of the Inter-American Court of Human Rights of December 21, 2010, sixth considering paragraph, and Case of Tibi v. Ecuador. Monitoring compliance with judgment, supra note 1, fourth considering paragraph. 3 Cf. Castillo Petruzzi et al. v. Peru. Monitoring compliance with judgment. Order of the Court of November 17, 1999, third considering paragraph; Case of the Miguel Castro Castro Prison v. Peru, supra note 2, sixth considering paragraph, and Case of Tibi v. Ecuador. Monitoring compliance with judgment, supra note 1, fourth considering paragraph. 4 Cf. Ivcher Bronstein v. Peru. Competence. Judgment of the Inter-American Court of Human Rights of September 24, 1999. Series C No. 54, para. 37; Case of the Miguel Castro Castro Prison v. Peru, supra note 2, seventh considering paragraph, and Case of Tibi v. Ecuador. Monitoring compliance with judgment, supra note 1, fifth considering paragraph. 5 Cf. Case of Barrios Altos v. Peru. Monitoring compliance with judgment. Order of the InterAmerican Court of Human Rights of September 22, 2005, seventh considering paragraph; Case of the Miguel Castro Castro Prison v. Peru, supra note 2, eighth considering paragraph, and Case of Garibaldi v. Brazil. Monitoring compliance with judgment. Order of the Inter-American Court of Human Rights of December of February 22, 2011, seventh considering paragraph. 6 It is worth noting that the documents forwarded by the State with its communication of June 29, 2009, already formed part of the file on monitoring compliance with the judgments delivered by the Court in this case, with the exception of two documents: (i) “The separate opinion of Supreme Court Justices Hugo Sivina Hurtado and José Luis Lecaros Cornejo, regarding the conviction of the defendant Juan Carlos Mejía León, [...],” and (ii) “The separate opinion of Justice Robinson Octavio Gonzales Campos, regarding the conviction of the defendant Juan Carlos Mejía León, [...].” 7 Cf. Case of Castillo Páez v. Peru. Monitoring compliance with judgment. Order of the InterAmerican Court of Human Rights of April 3, 2009, seventh to twenty-second considering paragraphs.