2 taking effect May 26, 1999 - pursuant to Article 78 of the Convention - given that the violations of the Pact took place before this last date. 5 Finally, the Court has demonstrated, in this same Judgment to which I attach my Separate Opinion, that the State cannot invoke provisions of its domestic law to avoid fulfilling its international treaty obligations. 6 It is important to note, as well, that Trinidad and Tobago ratified the Pact of San José on May 28, 1991, long after promulgating its Constitution. 3. The incompatibility of the Offences Against the Person Act with the American Convention, that I now propose to examine, and which has already been analysed and resolved by the Court in its Judgment, arises from the lack of agreement between the terms in which the Act prevents and sanctions murder, ordering the mandatory penalty of death penalty in the process, and the two provisions formulated under Article 4 of the American Convention concerning the death penalty. This implies a violation of Article 2 of the Pact of San José, in relation to Article 4, paragraphs 1 and 2 (to which could be added - as it will be shown below - paragraph 6 of this same precept). The relevant portion of paragraph 1 of Article 4 indicates that "[n]o one shall be arbitrarily deprived of his life" (emphasis added); and the relevant portion of paragraph 2 stipulates that "[i]n countries which have not abolished the death penalty, it may be imposed only for the most serious crimes" (emphasis added). There are, therefore, two definite restrictions on the imposition of the death penalty: One, which concerns the extreme seriousness of the crimes to which it may relate, and the other, the prohibition of arbitrariness in the deprivation of life. In my mind, the Offences Against the Person Act fails to respect these restrictions and as a result offends the American Convention that the State adopted and accepted as binding the respective obligations emanating from it, when it became a party to this international treaty. 4. Before examining these incompatibilities, it is important to recall that the Pact of San José does not abolish the death penalty. That widely demanded possibility derives from other national and international acts. 7 The American Convention 5 Cf. id., paras. 27-28. 6 This principle, found in Article 27 of the Vienna Convention on the Law of Treaties of 1969 (to which Trinidad and Trinidad and Tobago is not a party), constitutes a rule of customary international law. Article 27 "goes to the very foundation of international law, and for which there exist significant precedents." (translation of the Secretariat) De la Guardia, Ernesto, and Delpech, Marcelo, El Derecho de los tratados y la Convención de Viena, Buenos Aires, La Ley, 1970, p. 286. The Vienna Convention is in itself, in essence, a codification of preexisting international law, and as such affects even those states that have not ratified it. Cf. Harris, D. J., Cases and materials on International Law, London, Sweet & Maxwell, 1998, p.765; Van Hoof, G.J.H., Rethinking the sources of International Law, Deventer, The Netherlands, Kluwer Law and Taxation Publishers, 1983, No. 464; in a similar sense, Tunkin, Grigory, "Is general International Law Customary Law only?", European Journal of International Law, vol. 4, No. 4, 1993, pp. 534 and ff. With respect to the jurisprudence of the Inter-American Court in regard to the nonopposability of domestic law to the fulfillment of international obligations, cf. I/A Court H.R., 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; and I/A Court H.R., Castillo Petruzzi et al. Case. Compliance with Judgment. Order of November 17, 1999. Series C No. 59, considering 4. 7 Among the most recent are, the Protocol to the American Convention on Human Rights to Abolish the Death Penalty, June 8, 1990, and the Second Optional Protocol to the International Covenant on Civil and Political Rights, aiming at the abolition of the death penalty, adopted by the General Assembly of the United Nations on December 15, 1989.