Third Amendment of the Constitution of Ireland

The Third Amendment of the Constitution Act 1972 is an amendment to the Constitution of Ireland that permitted the State to join the European Communities, which would later become the European Union, and provided that European Community law would take precedence over the constitution. It was approved by referendum on 10 May 1972, and signed into law by the President of Ireland Éamon de Valera on 8 June of the same year.

Source: Wikipedia — Third Amendment of the Constitution of Ireland (CC BY-SA 4.0)