Article 50 Judgment of the Supreme Court

The Supreme Court has this morning handed down its eagerly-anticipated judgment on whether the Government has power under the Royal Prerogative to…

R (on the application of Santos & Miller) v Secretary of State for Exiting the European Union [2017] EWHC 2768


The Supreme Court has this morning handed down its eagerly-anticipated judgment on whether the Government has power under the Royal Prerogative to trigger the UK’s departure from the EU under Article 50 of the Treaty on European Union, or whether this power may only be conferred by a new Act of Parliament.

By a majority decision of 8 to 3, the Supreme Court has ruled against the Government’s appeal (Lords Reed, Carnwath and Hughes dissenting).  An Act of Parliament is therefore required in order to give notice under Article 50 of the UK’s decision to withdraw from the EU.

The Judgment

The Government, during its appeal, argued that ministers may make and unmake treaties by the exercise of the prerogative power in the international arena, and withdrawing from the EU Treaties would itself have no effect on statutory rights in domestic law. These rights would be amended by Parliament in due course, and in particular, when it repeals the 1972 European Communities Act (“ECA”), the legislation which provided for the application and supremacy in the UK of EU laws.  The ECA did not expressly exclude ministers’ power to withdraw from the EU Treaties and permitted the application of EU laws only for so long as the power of withdrawal had not been exercised.

The Supreme Court rejected the Government’s arguments, finding that there is a vital difference between variations in UK law resulting from changes in EU law (which the Government has power to implement), and variations in EU law which result from withdrawal from the Treaties.  Withdrawal will change fundamentally our constitutional arrangements, by cutting off the source of EU law.  When enacting the ECA, Parliament could have decided to authorise ministers to withdraw from the EU Treaties, but no such authority was given. On the contrary, the ECA requires ministers not to commit the UK to any new arrangement, whether increasing or decreasing the extent of EU law to which we are subject, without Parliamentary approval.  Withdrawal from the Treaties will, of course, potentially amount to a substantial decrease in the application of EU law in the UK.

The Supreme Court further held that the statute which facilitated last June’s EU referendum did not specify the legal consequences of a vote to leave the EU.  As such, the change in law necessary to effect Brexit must be made in the only way permitted by our constitution, namely by Act of Parliament.  The referendum therefore had political, but not legal, effect.

On devolution, Lord Neuberger providing the lead judgment described the Sewel Convention, under which the UK Parliament seeks consent of the Scottish Parliament before it legislates with regard to devolved matters, as a political constraint on the activities of the UK parliament.  Relationships with the EU and other foreign affairs are a matter for the UK Government and parliament, and the devolved legislatures have no veto on the UK’s decision to withdraw from the EU.

Read the full transcript of the Supreme Court judgment, and a shorter "Press Summary".

What next?

On 7 December 2016, the House of Commons passed a motion in support of the Prime Minister’s intention to trigger Article 50 by the end of March 2017, thereby setting the UK on course to exit the EU by March 2019.  It was acknowledged during the Supreme Court hearing, however, that this motion lacked the legal force of an Act of Parliament.  If the Government were to lose its case on appeal (as has now happened), it was common ground that a new Act of Parliament would therefore be required. 

The Commons’ motion did perhaps indicate that, if an Article 50 Bill must be presented for debate (and it must), it should at least be passed swiftly. However, the Commons’ motion was accompanied by a cross-party call for the Government to publish a plan for Brexit.  The Government responded to this call during the Prime Minister’s speech at Lancaster House last Tuesday (17January), the highlights of which were summarised in our previous Brexit update. However, the Government’s 12 key issues for negotiation have already proved more controversial with MPs than the timing of the Article 50 trigger.  It is likely therefore that a number of MPs will vote against the Bill, or will at least raise issues likely to delay its progress.

Although, ultimately, we should be surprised if Parliament fails to pass the legislation necessary to give effect to the stated wish of the electorate to leave the EU, the passage of the legislation may not be quite as smooth as the Government would wish.

Mike Yardley is a Professional Support Lawyer. To discuss any of the issues in this update please email

Share on Twitter