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, Ireland, uniquely in the EU, requires a plebiscite for every new, or substantive change to a, European Union Treaty.
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.
It is clear and was not otherwise contended by the defendants that the ratification by the State of the SEA (which has not yet taken place) would not constitute an act 'necessitated by the obligations of membership of the Communities'.
They noted that the Treaty of Rome provided for moving from unanimous voting to qualified majority and concluded that: The Community was thus a developing organism with diverse and changing methods for making decisions and an inbuilt and clearly expressed objective of expansion and progress, both in terms of the number of its Member States and in terms of the mechanics to be used in the achievement of its agreed objectives.
13)The Court ruled further that the "new" policy areas fell within the original objectives of the Treaty of Rome, that the creation of a new court would not increase the judicial power already delegated to the European institutions, and that the Plaintiff had failed to show how the new powers to be granted to the Council of Ministers could threaten constitutional rights.
105)The State's organs cannot contract to exercise in a particular procedure their policy-making roles or in any way to fetter powers bestowed unfettered by the Constitution.
106)The detailed terms of [Article 30 of the SEA] impose obligations to consult; to take full account of the position of other partners; to ensure that common principles and objectives are gradually developed and defined; as far as possible to refrain from impeding the formation of a consensus and the joint action which this could produce; to be ready to cooperate policies more closely on the political aspects of security.
They do not give to other High Contracting Parties any right to override or veto the ultimate decision of the State on any issue of foreign policy.
22)Having regard to the terms in which the provisions of Title III are expressed, I am in complete agreement with the Chief Justice in concluding that those provisions do not impose any obligations to cede any sovereignty or national interest in the field of foreign policy, nor do they in any way allow a decision of the State on any issue of foreign policy to be overridden or vetoed.
The Treaty, being an international agreement to which the State is a party, has been laid before and been approved by Dáil Éireann in compliance with the provisions of Article 29, s. 5, sub-ss.