This morning, the Supreme Court of the United Kingdom released its judgment in Miller and Dos Santos v Secretary of State for Exiting the European Union — the Brexit Article 50 case. The UK government was appealing its November 2016 loss in the High Court.

In a majority decision, eight of the Supreme Court's 11 judges dismissed the government’s appeal and upheld the High Court’s decision that Prime Minister Theresa May and her government do not have the power to invoke Article 50 of the Lisbon Treaty, which would begin the process of the UK’s exit from the European Union.

The Court confirmed that Parliament’s authorization is required before Brexit can be triggered. The judges were unanimous in finding that the government does not have to seek the consent of the devolved legislatures in Scotland, Wales and Northern Ireland to the legislation that will now need to be passed to give effect to Brexit.

Key aspects of the judgment

The Supreme Court’s press summary includes the following reasons for judgment:

  • The fact that withdrawal from the EU would remove some existing domestic rights of UK residents renders it impermissible for the government to withdraw from the EU Treaties without prior Parliamentary authority.
  • It would have been open to Parliament when enacting the European Communities Act 1972 (the ECA) to authorize ministers to withdraw from the EU Treaties, but clear words would have been required; not only are there no such clear words, but the provisions of the ECA indicate that ministers do not have such power.
  • The fact that ministers are accountable to Parliament for their actions is no answer constitutionally, if the power to act does not exist in the first place and where 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 the competences of the EU or its decision-making processes, but not to the giving of notice under Article 50(2), are entirely consistent with an assumption by Parliament that no power existed to withdraw from the treaties without a statute authorising that course.

The Court's press summary is available for download here, while the full decision is available here.

What happens next?

The Supreme Court's decision is not expected to delay the UK’s exit from the European Union. Prime Minister May has committed to triggering Article 50 by the end of March 2017. David Davis, Secretary of State for Exiting the European Union, stated in the House of Commons today that the government will introduce a bill within days.

Labour leader Jeremy Corbyn has signalled that Labour MPs will be encouraged to support any legislation that is put forward to trigger Article 50. Even accounting for opposition, it is anticipated that the legislation will pass in both Houses of Parliament.

To learn more, read Gowling WLG’s in-depth analysis of the Supreme Court’s decision and the next steps in the Brexit process.

Further background on the Brexit Article 50 case is outlined in our November 2016 summary of the High Court’s decision.