58 Report of the International Law Commission on the work of its fifty-third session conduct of British authorities who had seized United States vessels engaged in the slave trade and freed slaves belonging to United States nationals. The incidents referred to the Commission had taken place at different times and the umpire had to determine whether, at the time each incident took place, slavery was “contrary to the law of nations”. Earlier incidents, dating back to a time when the slave trade was considered lawful, amounted to a breach on the part of the British authorities of the international obligation to respect and protect the property of foreign nationals.220 The later incidents occurred when the slave trade had been “prohibited by all civilized nations” and did not involve the responsibility of Great Britain.221 (3) Similar principles were applied by Arbitrator Asser in deciding whether the seizure and confiscation by Russian authorities of United States vessels engaged in seal hunting outside Russia’s territorial waters should be considered internationally wrongful. In his award in the “James Hamilton Lewis” case, he observed that the question had to be settled “according to the general principles of the law of nations and the spirit of the international agreements in force and binding upon the two High Parties at the time of the seizure of the vessel”.222 Since, under the principles in force at the time, Russia had no right to seize the United States vessel, the seizure and confiscation of the vessel were unlawful acts for which Russia was required to pay compensation.223 The same principle has consistently been applied by the European Commission and the European Court of Human Rights to deny claims relating to periods during which the European Convention on Human Rights was not in force for the State concerned.224 (4) State practice also supports the principle. A requirement that arbitrators apply the rules of international law in force at the time when the alleged wrongful acts took place is a common stipulation in arbitration agreements,225 and undoubtedly is made by way of explicit confirmation of a generally recognized principle. International law writers who have dealt with the question recognize that the wrongfulness of an act must be established on the ba220 See the “Enterprize” case, Lapradelle-Politis (footnote 139 above), vol. I, p. 703 (1855); and Moore, History and Digest, vol. IV, p. 4349, at p. 4373. See also the “Hermosa” and “Créole” cases, Lapradelle-Politis, op. cit., p. 704 (1855); and Moore, History and Digest, vol. IV, pp. 4374–4375. 221 See the “Lawrence” case, Lapradelle-Politis, op. cit., p. 741; and Moore, History and Digest, vol. III, p. 2824. See also the “Volusia” case, Lapradelle-Politis, op. cit., p. 741. 222 Affaire des navires Cape Horn Pigeon, James Hamilton Lewis, C. H. White et Kate and Anna, UNRIAA, vol. IX (Sales No. 59.V.5), p. 66, at p. 69 (1902). 223 See also the “C. H. White” case, ibid., p. 74. In these cases the arbitrator was required by the arbitration agreement itself to apply the law in force at the time the acts were performed. Nevertheless, the intention of the parties was clearly to confirm the application of the general principle in the context of the arbitration agreement, not to establish an exception. See further the S.S. “Lisman” case, ibid., vol. III (Sales No. 1949.V.2), p. 1767, at p. 1771 (1937). 224 See, e.g., X v. Germany, application No. 1151/61, Council of Europe, European Commission of Human Rights, Recueil des décisions, No. 7 (March 1962), p. 119 (1961) and many later decisions. 225 See, e.g., Declarations exchanged between the Government of the United States of America and the Imperial Government of Russia, for the submission to arbitration of certain disputes concerning the international responsibility of Russia for the seizure of American ships, UNRIAA, vol. IX (Sales No. 59.V.5), p. 57 (1900). sis of the obligations in force at the time when the act was performed.226 (5) State responsibility can extend to acts of the utmost seriousness, and the regime of responsibility in such cases will be correspondingly stringent. But even when a new peremptory norm of general international law comes into existence, as contemplated by article 64 of the 1969 Vienna Convention, this does not entail any retrospective assumption of responsibility. Article 71, paragraph 2 (b), provides that such a new peremptory norm “does not affect any right, obligation or legal situation of the parties created through the execution of the treaty prior to its termination, provided that those rights, obligations or situations may thereafter be maintained only to the extent that their maintenance is not in itself in conflict with the new peremptory norm”. (6) Accordingly, it is appropriate to apply the intertemporal principle to all international obligations, and article 13 is general in its application. It is, however, without prejudice to the possibility that a State may agree to compensate for damage caused as a result of conduct which was not at the time a breach of any international obligation in force for that State. In fact, cases of the retrospective assumption of responsibility are rare. The lex specialis principle (art. 55) is sufficient to deal with any such cases where it may be agreed or decided that responsibility will be assumed retrospectively for conduct which was not a breach of an international obligation at the time it was committed.227 (7) In international law, the principle stated in article 13 is not only a necessary but also a sufficient basis for responsibility. In other words, once responsibility has accrued as a result of an internationally wrongful act, it is not affected by the subsequent termination of the obligation, whether as a result of the termination of the treaty which has been breached or of a change in international law. Thus, as ICJ said in the Northern Cameroons case: [I]f during the life of the Trusteeship the Trustee was responsible for some act in violation of the terms of the Trusteeship Agreement which resulted in damage to another Member of the United Nations or to one of its nationals, a claim for reparation would not be liquidated by the termination of the Trust.228 Similarly, in the “Rainbow Warrior” arbitration, the arbitral tribunal held that, although the relevant treaty obli226 See, e.g., P. Tavernier, Recherches sur l’application dans le temps des actes et des règles en droit international public: problèmes de droit intertemporel ou de droit transitoire (Paris, Librairie générale de droit et de jurisprudence, 1970), pp. 119, 135 and 292; D. Bindschedler-Robert, “De la rétroactivité en droit international public”, Recueil d’études de droit international en hommage à Paul Guggenheim (University of Geneva Law Faculty/Graduate Institute of International Studies, 1968), p. 184; M. Sørensen, “Le problème intertemporel dans l’application de la Convention européenne des droits de l’homme”, Mélanges offerts à Polys Modinos (Paris, Pedone, 1968), p. 304; T. O. Elias, “The doctrine of intertemporal law”, AJIL, vol. 74, No. 2 (April 1980), p. 285; and R. Higgins, “Time and the law: international perspectives on an old problem”, International and Comparative Law Quarterly, vol. 46 (July 1997), p. 501. 227 As to the retroactive effect of the acknowledgement and adoption of conduct by a State, see article 11 and commentary, especially paragraph (4). Such acknowledgement and adoption would not, without more, give retroactive effect to the obligations of the adopting State. 228 Northern Cameroons, Preliminary Objections, Judgment, I.C.J. Reports 1963, p. 15, at p. 35.