Relationship of international law and municipal law — Treaties — International Covenant on Civil and Political Rights, 1966 — Optional Protocol — Declaration — Sri Lankan Constitution — Sri Lanka acceding to Covenant — Sri Lanka acceding to Optional Protocol and making Declaration — Legal effect — Dualist theory of international law — Constitution of Sri Lanka — Sovereignty — Legislative, executive and judicial powers deriving from Constitution — Constitution limiting powers — Whether acts of President of Sri Lanka consistent with Constitution — Whether binding Republic qua State — Whether having legal effect within Republic — Whether findings of United Nations Human Rights Committee to be given effect by Supreme Court — The law of Sri Lanka