Crotty v An Taoiseach
Crotty v An Taoiseach is a landmark 1987 decision of the Irish Supreme Court which found that Ireland could not ratify the Single European Act unless the Irish Constitution was first changed to permit its ratification. The case, taken by Raymond Crotty formally against the Taoiseach (then Garret FitzGerald), directly led to the Tenth Amendment of the Constitution of Ireland (which authorised the ratification of the Single Act) and established that significant changes to European Union treaties required an amendment to the Irish constitution before they could be ratified by Ireland.