The Supreme Court rules on Article 50

Posted in UK and EU legal framework Devolution

Following one of the most important constitutional law cases to come before the UK courts, the Supreme Court has this morning handed down judgment in the UK Government’s appeal against the earlier decision of the High Court that parliamentary approval is needed to give notice under Article 50 of the Treaty of European Union1, the formal treaty mechanism by which a Member State exits from the European Union. 

The decision, by a majority of 8-3, upholds the High Court’s earlier decision and means that the Government cannot invoke Article 50 without first obtaining the approval of Parliament.

The case is constitutionally significant in the opportunity it provided for the Supreme Court to give important legal clarification on the relationship between Executive and Legislature (Government and Parliament) and the proper role and powers of each in the specific context of the Article 50 question.

The central issue: the power to invoke Article 50

The appeal to the Supreme Court by the UK Government sought to determine whether the Government was entitled to exercise its prerogative powers to trigger Article 50.  The Government had argued that the making or withdrawing from international treaties fell within the prerogative powers. The High Court had previously agreed with the Claimants’ submissions that the UK Government was not able to act unilaterally if the effect of serving notice under Article 50 would be to override statutory rights of citizens brought into domestic law by the European Communities Act 1972 unless Parliament had conferred on it the authority to do so. The High Court concluded that the ECA confers no such authority either expressly or by necessary implication.

The High Court’s reasoning relied on the premise that insofar as it had been accepted by the UK Government that an Article 50 notification was irrevocable, mere notification would inevitably change domestic law and affect rights (although in a similar challenge before the Northern Ireland High Court, that court had held that there was nothing in the Northern Ireland Act 1998 or the Good Friday Agreement which prevented the UK Government triggering Article 50 under the prerogative powers).  

The Supreme Court’s judgment on Article 50

At para.69 of the judgment, the majority noted that it was common ground that domestic law will change as a result of the UK ceasing to be part of the EU and rights granted under EU law will be affected (although Lord Carnwath, dissenting, took the view that service of an Article 50 notice will not of itself change any laws or affect any rights).

The majority of the Supreme Court agreed with the High Court that the Government cannot trigger Article 50 without the approval of Parliament. The reasoning again involved a question of statutory interpretation: the majority took the view that the terms of the ECA, which gave effect to the UK’s membership of the EU, are inconsistent with the exercise by the Government of any power to withdraw from the EU without authorisation by a prior Act of Parliament.

The majority referred to section 2 of the ECA which establishes EU as a source of domestic law, taking precedence over existing sources of domestic law.  They rejected the Government’s arguments that (i) the ECA does not exclude the power for ministers to withdraw from the EU Treaties, and (ii) that section 2 of the ECA actually caters for the exercise of such a power as it gives effect to EU law only so long as the power of withdrawal is not exercised. 

Instead, the majority considered that there is 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. In their view, “A complete withdrawal represents a change which is different not just in degree but in kind from the abrogation of particular rights, duties or rules derived from EU law. It will constitute as significant a constitutional change as that which occurred when EU law was first incorporated in domestic law by the 1972 Act ... It would be inconsistent with long-standing and fundamental principle 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” (para.81).

Withdrawal from the EU would result in a fundamental change to the UK’s constitutional arrangements, by cutting off the source of EU law which would be the inevitable effect of Article 50 being triggered.  According to the majority at paragraph 83, “section 2 of [the ECA] envisages domestic law, and therefore rights of UK citizens, changing as EU law varies, but it does not envisage those rights changing as a result of ministers unilaterally deciding that the United Kingdom should withdraw from the EU Treaties.”

The majority added that the “improbability of the Secretary of State’s case is reinforced by the point that, if, as he contends, prerogative powers could be invoked in relation to the EU Treaties despite the provisions of the 1972 Act, it would have been open to ministers to take such a course on or at any time after 2 January 1973 without authorisation by Parliament. It would also follow that ministers could have taken that course even if there had been no referendum or indeed, at least in theory, even if any referendum had resulted in a vote to remain. Those are implausible propositions” (para.91).

They concluded that “If ministers give Notice without Parliament having first authorised them to do so, the die will be cast before Parliament has become formally involved. To adapt Lord Pannick’s metaphor, the bullet will have left the gun before Parliament has accorded the necessary leave for the trigger to be pulled. The very fact that Parliament will have to pass legislation once the Notice is served and hits the target highlights the point that the giving of the Notice will change domestic law: otherwise there would be no need for new legislation” (para.94).

The Devolution debate

The Supreme Court also heard submissions regarding the position of devolved nations and the argument over the ambit of what is known as the Sewel Convention.2 The Sewel Convention provides that although parliamentary sovereignty allows the UK Government to repeal or amend legislation, changes to legislation affecting devolved powers are normally subject to the passing of a legislative consent motion by the parliament concerned.  In other words, although it has power to do so, the UK Parliament will not normally legislate on devolved matters without the consent of the devolved legislation. It should be noted that in the case of Scotland, the convention was given statutory effect by the Scotland Act 2016.  This amended the Scotland Act by adding, as a new section 28(8) of the Scotland Act 1998 “… it is recognised that the Parliament of the United Kingdom will not normally legislate with regard to devolved matters without the consent of the Scottish Parliament.”

On the devolution issue, the Supreme Court was unanimous in holding that the UK Government was not legally required to consult the devolved administrations.  Although the various devolution Acts were passed on the assumption that the UK would be a member of the EU, the Supreme Court concluded that they do not require this to be the case.  The question of whether the UK remains a member of the EU is reserved to the UK Parliament and Government. Whilst noting the importance of the Sewel Convention, the Supreme Court concluded that this was not something it could rule on. 

This aspect of the decision, although widely expected, is important as it removes any suggestion that the devolved administrations will be able to exercise a veto over Brexit.

What happens next?

The Supreme Court confirmed that what is required is an Act of Parliament rather than a simple resolution (paras.121-123) – something which the UK Government had appeared to accept following the original decision of the High Court.  This is expected to be tabled in the coming days.

There has been speculation that this could simply be a short Bill.  The majority of the Supreme Court made clear that the form such legislation will take is entirely a matter for Parliament, noting that there is “no equivalence between the constitutional importance of a statute … and its length or complexity” (paras.122).

The Government’s aim will no doubt be to push the necessary legislation through Parliament as quickly as possible on the basis that MPs would be expected to honour the referendum result and it is still unclear the extent to which opponents will push for amendments and the extent to which such amendments would seek to constrain the Government – particularly in view of Theresa May’s recent speech setting out the Government’s objectives for Brexit (as to which see our previous post). 

More legal challenges on the horizon?

Although the decision of the Supreme Court is final as far as this challenge is concerned, other legal challenges loom on the horizon.

The UK Government faces a separate judicial review challenge in relation to the UK’s EEA membership and whether the UK remains part of the single market. This is likely to include consideration of the question of whether on Brexit, the UK would nevertheless remain part of the EEA unless separate notice were to be given under Article 127 of the Agreement on the European Economic Area – which provides for 12 months’ written notice to exit.  

A legal challenge against the Irish Government, European Commission and Council of Ministers has also been lodged in Ireland, seeking, amongst other things, clarification as to whether an Article 50 notice can be revoked: a question which might then need to be referred to the European Court of Justice in Luxembourg and which was studiously avoided in the Article 50 proceedings before the English courts.

Legal debates and challenges in relation to Brexit are set to continue throughout 2017.


1. As amended by the Treaty of Lisbon 2007.

2. The Sewel Convention was initially based on a Memorandum of Understanding between the UK Government and the devolved executives, which was drawn up in 1999 setting out a statement of principles for relations between the executive authorities in the UK, Scotland, Wales and Northern Ireland. The Memorandum was not intended to be legally binding, but does represent a political undertaking. Source: House of Commons briefing paper SN02084.


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