See IG, Advisory Opinion on the Interpretation of Peace Treaties with Bulgaria, Hungary and Romania (1949-1950) of 18 July 1950 (IG Reports 1950,p. Moreover, an international instrument has to be interpreted and applied within the framework of the entire legal system prevailing at the time of the interpretation. Advisory Opinion on the 'Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa), notwithstanding Security Council Resolution 276 (1970)', (ICJ Reports 1971, p. 16, para. See, e.g., the case of Tyrer v. the United Kingdom, Application No.