Brexit: Statute required to trigger Article 50, says Supreme Court

Thursday 26 January 2017

Authors: Ian Gault and Matthew Davie

On 24 January 2017 the UK Supreme Court delivered its decision in the “Brexit case”, R (on the application of Miller and another) v Secretary of State for Exiting the European Union. By a majority of eight to three, the Court upheld the decision of the High Court that only Parliament has the authority to trigger Article 50 of the Treaty on the European Union. Article 50 is the formal notice by which a member state has to give notice of its intention to leave the EU. Once Article 50 is triggered, the UK will likely leave the EU within two years.

The Court also unanimously held that the devolved legislatures of Scotland, Northern Ireland and Wales could not veto a Parliamentary decision to trigger Article 50.

The Court’s decision sets the stage for a showdown in Parliament between Theresa May’s Government and MPs who seek a “soft Brexit”, MPs who seek to delay Brexit, and MPs who hope to avoid Brexit entirely.

The decision

At its core, Miller is about the extent of the executive’s power. It is the latest in a long line of UK decisions going back centuries which define and limit the power of the executive government. The UK Government argued that it possessed the power – via the royal prerogative vested in the Queen – to trigger Article 50. It argued that the decision to trigger Article 50 is no different from a decision to withdraw from a treaty, which is within the ambit of the royal prerogative. Conversely, Ms Miller argued that the decision to trigger Article 50 is special: doing so irrevocably commits the UK to leaving the EU, with attendant effects on the UK legal system and the rights and obligations of UK citizens and residents. As such, only an Act of Parliament can trigger Article 50.

The majority of the Court agreed with Ms Miller. Lord Neuberger, with whom Lady Hale and Lords Mance, Kerr, Clarke, Wilson, Sumption and Hodge agreed, conceptualised the European Communities Act 1972 (the 1972 Act) as a “conduit pipe” through which EU Law flowed into the UK and became part of the law of the land (“so long as the 1972 Act remains in force, its effect is to constitute EU law an independent and overriding source of domestic law” - paragraph 65). Withdrawal from the EU would effectively dismantle this conduit pipe, even if the 1972 Act was not formally repealed.

    Paragraph 80
    Upon the United Kingdom’s withdrawal from the European Union, EU law will cease to be a source of domestic law for the future ... Even those legal rules derived from EU law and transposed into UK law by domestic legislation will have a different status. They will no longer be paramount, but will be open to domestic repeal or amendment in ways that may be inconsistent with EU law

The majority reasoned that dismantling the conduit pipe would amount to changing UK law, and as such fell within the sole competence of Parliament.

    Paragraph 81
    It would be inconsistent with long-standing and fundamental principles for such a far-reaching change to the UK constitutional arrangements to be brought about by ministerial decision or ministerial action alone. All the more so when the source in question was brought into existence by Parliament through primary legislation, which gave that source an overriding supremacy in the hierarchy of domestic law sources.

The majority specifically upheld the High Court’s reasoning that the UK Government could not trigger Article 50 without Parliamentary authorisation because doing so would affect the rights of UK citizens and residents (paragraph 83).

The three dissenting judges, Lords Reed, Carnwath and Hughes, each wrote separate judgments. They disagreed with the majority’s view that Parliament intended that only it could cause the UK to withdraw from the EU. They held that nothing in the 1972 Act or later legislation provided expressly or by implication that the executive would not be able to exercise the royal prerogative to trigger Article 50.

The Court dealt with a number of devolution questions referred by the High Court of Northern Ireland and the Northern Ireland Court of Appeal. The Court was asked whether the Northern Ireland Act 1998 required that Parliament obtain the consent of the people of Northern Ireland before triggering Article 50. The Supreme Court unanimously rejected this. While the Northern Ireland Act 1998 provides for the possibility that Northern Ireland could cede from the UK, nothing in the Act restrains Parliament’s power to leave the EU.

The Court considered whether the Sewel Convention gives the devolved legislatures of Northern Ireland, Scotland and Wales a right to veto Article 50. Under the Sewel Convention (named after Lord Sewel, the minister responsible for the progress of the Scotland Bill in 1998), Parliament will exercise its right to legislate in respect of Scotland and other regions with devolved legislatures in matters within or affecting the legislature’s competence only after seeking and obtaining the consent of the legislature in question. The Court unanimously held that the Sewel Convention did not give the devolved legislatures the right to veto Article 50 because a convention is a political document which is unenforceable in the courts.

    Paragraph 146
    Judges therefore are neither the parents nor the guardians of political conventions; they are merely observers. As such, they can recognise the operation of a political convention in the context of deciding a legal question ... but they cannot give legal rulings on its operation or scope, because those matters are determined within the political world. As Professor Colin Munro has stated, “the validity of conventions cannot be the subject of proceedings in a court of law” - (1975) 91 LQR 218, 228

Additionally, the Court held that Article 9 of the Bill of Rights Act 1689, which provides that “Proceedings in Parliament ought not to be impeached or questioned in any Court or Place out of Parliament” was a further reason for rejecting the Sewel Convention argument (paragraph 145).

What happens next?

The UK Government quickly confirmed it will comply with the Court’s decision. According to early media reports, the UK Government will now submit a bill to the House of Commons which will provide for triggering Article 50 by the end of this week. The government has said it will produce a white paper which will set out its plans for implementing Brexit, although it is not clear whether this will be available before Parliament votes on the bill. It appears that a majority of MPs will vote to authorise the UK Government to trigger Article 50. However, the Labour Party and the Scottish National Party have said that they intend to table amendments to the bill. The government may also encounter difficulties in the House of Lords, of which a large number of members oppose leaving the EU.

The UK Government will likely succeed in obtaining Parliamentary authorisation for triggering Article 50. However, the number of hurdles the government must jump over suggests a risk that it may well miss its target of the end of March 2017 for triggering Article 50. There is also a risk that the government will be forced into backing down from its policy of seeking a “hard Brexit”. For example. leaving the EU single market and customs union as well as the EU, may require at least to disclose to Parliament more of its hand in its negotiating strategy with the EU.

Miller may not be the UK Government’s last foray into the courts in respect of Brexit. According to media reports, UK Barrister John Maugham QC intends to file proceedings in the High Court of Ireland for the purpose of obtaining a reference to the European Court of Justice on the question of whether an Article 50 notice can be revoked once issued.

Implications for New Zealand

In all likelihood, the UK Supreme Court’s decision does not change the ultimate outcome of Brexit:  the UK will leave the EU, including the single market, and will negotiate a new free trade deal of some sort with the EU. Accordingly, New Zealand will still be able to pursue its policy of seeking new free trade deals with both the UK and the EU.

However, Miller has at least raised the possibility – albeit remote – that Parliament will refuse to trigger Article 50 or soften the hard Brexit strategy of the UK Government and seek to stay within the single market. Parliament’s involvement may also delay the triggering of Article 50. Accordingly, a New Zealand-UK free trade deal may take longer. Financial markets may have felt the added uncertainty created by Miller: the GBP was down 0.6 per cent against the USD overnight after the decision was released.


This publication is necessarily brief and general in nature. You should seek professional advice before taking any action in relation to the matters dealt with in this publication.

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