Crotty v. An Taoiseach was 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. As a consequence, the Republic of Ireland, uniquely in the EU, requires a plebiscite for every new, or substantive change to a, European Union Treaty. The substantive issues in the case revolved around the interpretation of Part III of the Single European Act which codified cooperation on foreign policy matters between the governments of the then twelve member states of the European Economic Community – referred to as European Political Cooperation – into an international agreement. The majority of the Court ruled that if the state ratified Part III, it would amount to an unconstitutional delegation of the state's external sovereignty. The dissenting judges argued that the provisions only constituted a requirement to listen and consult. Supreme Court decision The Supreme Court decision was split into two parts. The first dealt with the constitutionality of the European Communities (Amendment) Act 1986 and consequently the first two parts of the Single European Act. The Constitution requires that the Supreme Court only hand down a single judgement in such circumstances. The second part of the Court's decision considered Raymond Crotty's challenge to the proposed ratification of Part III of the Single European Act. As this did not involve a challenge to the constitutionality of legislation, each judge is free to hand down separate judgements. In a 3-2 decision a majority of the Court found Part III to be repugnant to the Constitution. European Communities (Amendment) Act 1986 The judgement of the Court on the constitutionality of the 1986 Act was given of Finlay CJ. The Court first considered where the 1986 Act could take advantage of the Third Amendment which granted constitutional immunity to legal measures which were necessitated by membership of the European Communities. The Court then continued: The plaintiff made four arguments challenging the constitutionality of the 1986 Act. These were: that the Act unlawfully surrendered Irish sovereignty by