Keywords: Marriage Equality; Sexual Orientation; Non-discrimination; Judgments of National Courts; State Practice; Customary Rules
On 26 June 2015 the United States Supreme Court ruled that same-sex marriage is a fundamental constitutional right that cannot be infringed. This decision represents an important step in the civil rights revolution process started with the end of the separate but equal doctrine in public education. The judgment is founded on two clauses of the Constitution: the equal protection clause and the due process clause. Nevertheless this article considers it in the light of international law. The line of reasoning of the Court is analysed in order to see whether the opinion of the Court can be regarded as state practice for the purpose of creating international law. Some doubts have been cast on the very possibility of using national judicial decisions as elements of state practice. Moreover, according to some scholars, there is no general international customary law in the field human rights, but only principles. This is not however the universal view and the article contains an attempt to show the possibility of using an internal decision based on constitutional law as state practice relevant for international law. In addition to that the article illustrates the feasibility of the development of a custom-base norm in the field of non-discrimination for sexual orientation.