R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5

Following the 2016 EU referendum, the Government sought to trigger Article 50 TEU using prerogative powers. The Supreme Court held 8-3 that an Act of Parliament was required before ministers could notify withdrawal from the EU, as the 1972 Act created domestic legal rights that could not be removed by executive action alone.

Facts

Following the referendum on 23 June 2016, in which a majority voted to leave the European Union, the UK Government announced its intention to give notice of withdrawal under Article 50 of the Treaty on European Union. Gina Miller and others challenged the Government’s power to trigger Article 50 using prerogative powers without prior Parliamentary authorisation. The European Communities Act 1972 had incorporated EU law into UK domestic law, creating rights enforceable in UK courts.

Issues

Principal Issue

Whether ministers could lawfully give notice under Article 50(2) TEU to withdraw from the European Union using prerogative powers, or whether an Act of Parliament was required.

Devolution Issues

Whether provisions of the Northern Ireland Act 1998, or the Sewel Convention, required the consent of devolved legislatures before such legislation could be enacted.

Judgment

The Supreme Court, by a majority of 8-3, dismissed the Secretary of State’s appeal. The Court held that ministers could not give notice under Article 50 without prior authorisation from Parliament in the form of primary legislation.

Majority Reasoning

The majority held that the 1972 Act had unprecedented constitutional effects, constituting EU law as an independent and overriding source of domestic law. Lord Neuberger, delivering the majority judgment, stated:

By the 1972 Act, Parliament endorsed and gave effect to the United Kingdom’s membership of what is now the European Union under the EU Treaties in a way which is inconsistent with the future exercise by ministers of any prerogative power to withdraw from such Treaties.

The Court emphasised that withdrawal would constitute a fundamental change in constitutional arrangements:

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.

Minority View

Lord Reed, Lord Carnwath and Lord Hughes dissented. Lord Reed argued that the effect given to EU law under the 1972 Act was inherently conditional on the Treaties applying to the UK, and therefore no further legislation was required.

Devolution and Sewel Convention

The Court unanimously held that the Sewel Convention, although recognised in statute, remained a political convention that courts could not enforce:

The policing of its scope and the manner of its operation does not lie within the constitutional remit of the judiciary, which is to protect the rule of law.

Accordingly, the consent of the Scottish Parliament, Welsh Assembly, or Northern Ireland Assembly was not legally required.

Implications

This decision affirmed Parliamentary sovereignty as the fundamental principle of the UK constitution. It established that where prerogative action would fundamentally alter domestic constitutional arrangements or remove rights created by statute, Parliamentary authority is required. The case led directly to the European Union (Notification of Withdrawal) Act 2017. The ruling also clarified that constitutional conventions, even when given statutory recognition, remain political rather than legal constraints and cannot be judicially enforced.

Verdict: Appeal dismissed by majority of 8-3. Ministers require authorisation by Act of Parliament before giving notice under Article 50 TEU. Devolution questions answered: consent of devolved legislatures is not a legal requirement.

Source: R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5