By Mark McKeown, Associate and Hannah Starritt, Solicitor

The High Court of England and Wales has handed down its judgment in the case known as R (Gina Miller and Deir Tozetti Dos Santos) v Secretary of State for Exiting the European Union.

The full text of the judgment can be found here.

The claimants in this case did not dispute or seek to overturn the result of the UK’s recent EU Referendum, but instead sought to challenge the manner in which it will be taken forward. The question posed to the Court was whether, as a matter of UK law, the UK Government is entitled to give notice of a decision to leave the European Union (EU) under Article 50 of the ‘Lisbon Treaty’ by exercise of the Crown’s prerogative power, and without reference to the UK Parliament.

The Court decided that the Government does not have the power under the Crown prerogative to give notice under Article 50 for the UK to withdraw from the EU. This means that the Government cannot, as it had intended, lawfully invoke Article 50 by itself.

The Parliamentary Sovereignty of the UK Constitution

The claimants argued that the Government will be unable to issue a declaration under Article 50 without having first been authorised to do so by the UK Parliament, by way of an Act of Parliament. They based this assertion on the fact, amongst others, that the UK is a parliamentary democracy and that the EU Referendum was advisory and not binding. Accordingly, they argued that the UK Parliament should ultimately decide on the timing and manner of triggering Article 50, and the implications of the Referendum on the rights of British citizens, flowing from their membership of the EU. They also claimed that there is a conflict between the European Communities Act 1972 and the prerogative power which the Government intends to use in order to trigger Article 50.

The Court held that the most fundamental rule of the UK’s constitution is that the UK Parliament is sovereign and can make and unmake any law it chooses, and that it is established that the Crown (i.e. the Government of the day) cannot by exercise of prerogative powers override legislation enacted by Parliament.

The Government’s Argument for Royal Prerogative Powers

The Government relied on the argument that the conduct of international relations and of making and unmaking treaties are taken to be matters falling within the scope of the Crown’s prerogative powers. This rule exists as such prerogative powers have no effect on domestic law, including as laid down by Parliament by legislation. It accepted that if notice to leave the EU is given under Article 50 it will inevitably have the effect of changing domestic law.

The Government further argued that the UK Parliament must be taken to have intended that when it enacted the 1972 Act, the Crown could retain its prerogative power to effect a withdrawal from the EU, and that it was intended that the Crown should have the power to choose whether EU rules should continue to have effect on UK domestic law.

The Court did not agree with this argument, noting that it was contrary to both the language used in the 1972 Act and the fundamental constitutional principles of the sovereignty of the UK Parliament.

The Government plans to appeal the decision to the UK Supreme Court, with the hearing expected to take place in early December.