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Parliament must decide on EU withdrawal notice, Supreme Court rules

24 January 2017

Parliament must give its authority by legislation before the UK Government can begin the formal process of withdrawing the country from the European Union, the UK Supreme Court ruled today.

However the court, which voted by eight justices to three against the UK Government’s contention that it was entitled under prerogative powers to give notice to the EU without reference to Parliament, was unanimous that none of the devolved legislatures had any right to a say in such legislation.

The court, sitting as a bench of all 11 Justices, was ruling on the Government's appeal against the High Court ruling in November that the Secretary of State for Exiting the European Union did not have power to give notice as required by article 50 of the Treaty on the European Union, without Parliament’s prior authority.

Gina Miller and Deir Dos Santos, the principal claimants, maintained that owing to the well established rule that prerogative powers may not extend to acts which result in a change to UK domestic law, and withdrawal from the EU Treaties would change domestic law, the Government could not serve notice unless first authorised to do so by an Act of Parliament.

The appeal was joined with an appeal from the Northern Ireland High Court, which dismissed an application that contended that the devolution settlement for the province required the Northern Ireland Assembly to consent to, or at least be consulted on, the notice. The Scottish and Welsh Governments were allowed to intervene in the appeals to argue for similar rights.

On the main issue, Lord Neuberger, Lady Hale, Lord Mance, Lord Kerr, Lord Clarke, Lord Wilson, Lord Sumption and Lord Hodge made up the majority against the Government, while Lord Reed, Lord Carnwath and Lord Hughes dissented.

In a joint judgment delivered by Lord Neuberger, the President, the court ruled that the terms of the European Communities Act 1972, which gave effect to the UK’s membership of the EU, were inconsistent with the exercise by ministers of any power to withdraw from the EU Treaties without authorisation by a prior Act of Parliament.

Section 2 of the ECA authorised a dynamic process by which EU law became a source of UK law and took precedence over all domestic sources of UK law, including statutes. So long as the Act remained in force, its effect was to constitute EU law as an independent and overriding source of domestic law. It was common ground that UK domestic law would change as a result of the UK ceasing to be party to the EU treaties, and the rights enjoyed by UK residents granted through EU law would be affected.

Regarding the Government's argument that the 1972 Act does not exclude the power for ministers to withdraw from the EU Treaties, and that s 2 actually caters for the exercise of such a power, there was a vital difference between variations in UK law resulting from changes in EU law, and variations in UK law resulting from withdrawal from the EU Treaties. Withdrawal made a fundamental change to the UK’s constitutional arrangements, by cutting off the source of EU law. That was the inevitable effect of a notice being served, and the UK constitution required such changes to be effected by parliamentary legislation. The fact that withdrawal from the EU would remove some existing domestic rights of UK residents also rendered it impermissible for the Government to withdraw from the EU Treaties without prior parliamentary authority.

It was no answer constitutionally that ministers were accountable to Parliament for their actions, if the power to act did not exist in the first place and (as the court was asked to assume) the exercise of the power would be irrevocable and pre-empt any parliamentary action. Subsequent EU-related legislation and events after 1972, including the introduction of parliamentary controls in relation to decisions made by UK ministers at EU level relating to EU competences or decision-making processes, were entirely consistent with an assumption by Parliament that no power existed to withdraw from the treaties without a statute authorising that course.

The judges observed that while the 2016 referendum was of great political significance, the statute authorising it simply provided for the referendum to be held without specifying the consequences. The change in the law required to implement the outcome had to be made in the only way permitted by the UK constitution, namely by legislation.

The minority considered that the effect Parliament had given to EU law under the 1972 Act was inherently conditional on the application of the EU treaties to the UK and therefore on the UK’s membership of the EU, and the Act did not affect the Crown’s exercise of prerogative powers in respect of UK membership. Lord Carnwath observed that service of notice under article 50 was merely the start of an essentially political process of negotiating and decision making; the Government would be accountable to Parliament for those negotiations and the process could not be completed without the enactment by Parliament of primary legislation in some form.

On the devolution issues, the devolution Acts were passed by Parliament on the assumption that the UK would be a member of the EU, but they did not require the UK to remain a member. Relations with the EU and other foreign affairs matters are reserved to UK Government and parliament, not to the devolved institutions.

The decision to withdraw from the EU was not a function carried out by the Secretary of State for Northern Ireland in relation to Northern Ireland within the meaning of s 75 of the Northern Ireland Assembly Act. As to the application of the Sewel Convention in relation to the Scottish Parliament, it operated as a political constraint on the activity of the UK Parliament, and therefore played an important role in the operation of the UK constitution, but the policing of its scope and operation was not within the constitutional remit of the courts.

Click here to access the judgments.


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