SAVICKIS AND OTHERS v. LATVIA JUDGMENT empowered to pass formal judgment on the legality or legitimacy of any transfer of sovereignty under international law (see Ukraine v. Russia (re Crimea) [GC] (dec.), nos. 20958/14 and 38334/18, § 339, 16 December 2020), be it current or historical. Moreover, in principle, given the subsidiary nature of the Convention system, it is not the Court’s task to substitute itself for the domestic courts, particularly in cases where they assess facts of some historical sensitivity (see, among many other authorities, Vasiliauskas v. Lithuania [GC] (no. 35343/05, § 160, ECHR 2015). 103. On the other hand, the Court has always held that the provisions of the Convention cannot be interpreted and applied in a vacuum. Despite its specific character as a human rights instrument, the Convention is an international treaty to be interpreted in accordance with the relevant norms and principles of public international law. Thus, the Court has never considered the provisions of the Convention to be the sole frame of reference for the interpretation of the rights and freedoms enshrined therein. On the contrary, it must also take into account any relevant rules and principles of international law applicable in relations between the Contracting Parties (see, among many other authorities, Al-Dulimi and Montana Management Inc. v. Switzerland [GC], no. 5809/08, § 134, 21 June 2016, and Naït-Liman v. Switzerland [GC], no. 51357/07, § 174, 15 March 2018). The Court has also repeatedly held that, while it is not its function to deal with errors of fact or law allegedly committed by national courts – unless and in so far as they may have infringed rights and freedoms protected by the Convention and unless that domestic assessment is arbitrary or manifestly unreasonable – it can accept certain well-known historical truths and base its reasoning on them. This principle also applies where domestic law refers to rules of general international law or international agreements, and where domestic courts apply principles of international law (see Vasiliauskas, cited above, ibid., with further references). However, the Court is empowered to do so in so far as and only to the extent necessary for the exercise of its competence under Article 19 of the Convention as defined above (see Ukraine v. Russia (re Crimea), decision cited above, § 341). 104. As far as Latvia is concerned, the Court notes that its official position as expounded in the judgment of the Constitutional Court of 17 February 2011 and in the written observations of the respondent Government in the present case (see paragraphs 55 and 98-99 above) may be summarised as follows. Latvia (as well as the neighbouring Baltics States of Lithuania and Estonia) was a victim of aggression, unlawful occupation and annexation on the part of the former Soviet Union, starting from 1940. Therefore, Latvia is not a successor state to the USSR; it retains the statehood that existed when its independence was lost de facto in 1940 but which nevertheless remained in place de jure throughout the entire Cold War period. In other words, Latvia never disappeared de jure, although its independence was forcibly interrupted de facto for a half-century as a result of a blatant breach of international law. 37