SAVICKIS AND OTHERS v. LATVIA JUDGMENT Security Council Resolution 276 (1970), [1971], ICJ Reports 16, p. 56), as well as to the Court’s own judgments in the cases of Cyprus v. Turkey [GC] (no. 25781/94, ECHR 2001-IV); Catan and Others v. the Republic of Moldova and Russia [GC] (nos. 43370/04 and 2 others, ECHR 2012 (extracts)); and Ukraine v. Russia (re Crimea) [GC] (dec.) (nos. 20958/14 and 38334/18, 16 December 2020). Since Latvia did not exercise such effective control or jurisdiction, no obligation in the field of social security for the disputed years could fall on this State. To conclude otherwise would lead to a manifestly unreasonable interpretation of the Convention, that is, directly deriving a legal benefit from an illegal act, in violation of the legal maxim “ex injuria ius non oritur”. (b) The applicants 100. The applicants considered that the State continuity doctrine was not relevant for the purposes of the present case. Although the Republic of Latvia was indeed not directly responsible for the actions of the former Soviet Union, it could not simply ignore the de facto interruption of its statehood for fifty years. Moreover, Latvia was required to fulfil obligations in the field of fundamental rights that it had undertaken both at the domestic level and by ratifying the Convention. Even if Latvia was not a successor State to the USSR, it had expressly assumed responsibility for former Soviet citizens who settled in that country during the Soviet period. In this regard, the applicants referred to the Declaration of 4 May 1990 on the Restoration of Independence of the Republic of Latvia, in which Latvia expressly took the commitment “to guarantee social, economic and cultural rights ... to citizens of the USSR who wish to live in Latvia without acquiring Latvian nationality” (see paragraph 61 above). The applicants therefore invited the Court to reaffirm its finding in the Andrejeva judgment according to which the respondent Government’s reference to the State continuity doctrine is “misconceived” (ibid., § 78). 2. Submissions of the third-party intervener 101. The Russian Government stated that, during the period in question, Latvia had been a full-fledged part of the Soviet Union. They submitted that the terms “Soviet occupation”, “Sovietisation” and “Russification” were controversial and extra-legal categories which could not justify the application of discriminatory provisions thirty years after Latvia had become independent. 3. The Court’s assessment 102. The Court points out that its jurisdiction is delineated by Article 19 of the Convention, according to which its sole duty is “[t]o ensure the observance of the engagements undertaken by the High Contracting Parties in the Convention and the Protocols thereto”. Accordingly, the Court is not 36