Can the UK reverse its decision to leave the EU?
We consider a bombshell ruling of legal and political significance in the Brexit process. In a move described as 'disappointing' by the Government, the European Court of Justice (ECJ) will be asked if the UK can unilaterally revoke its Article 50 request to leave the European Union.
Scotland's highest court has agreed to refer the fundamental question of whether EU law permits unilateral revocation of an Article 50 withdrawal notice to the ECJ (Wightman and others v Secretary of State for Exiting the European Union  CSIH 62 P1293/17 (21 September 2018)).
The ECJ's decision is expected before Christmas and, depending on the outcome, could be a catalyst for a 'no Brexit' parliamentary vote or even a second referendum.
Article 50 of the Treaty on EU provides a legal mechanism for a member state to withdraw from the EU.
On 23 June 2016, a referendum of the UK electorate (European Union Referendum Act 2015) produced a majority in favour of leaving the EU.
Following R (Miller) v Secretary of State for Exiting the European Union  AC 61, the European Union (Notification of Withdrawal) Act 2017 conferred power on the Prime Minister to notify the UK’s intention to withdraw from the EU under Article 50.
Article 50 was triggered by Teresa May on 29 March 2017, and following a two-year divorce negotiation, the UK is due to leave the EU on 29 March 2019. However, negotiations between the EU and the UK have so far failed to reach a positive outcome, increasing the risk that the UK will crash out of the EU on 29 March 2019 without any trade deal in place.
The Scottish referral to the ECJ therefore comes at a crucial point in the negotiations.
The issue for the Court of Session
Following the Government's notification under Article 50, a petition was lodged before the Court of Session by a cross-party group of politicians, including members of the Scottish, UK and European Parliaments (the Petitioners).
The Petitioners sought a declaration specifying whether the notification could be unilaterally revoked before expiry of the two-year period, with the effect that the UK would remain in the EU.
An answer could only be given by the ECJ, so the Petitioners sought a reference under Article 267 of the Treaty on the Functioning of the EU.
At an interim hearing by the Court of Session earlier this year, the court declined to make a reference to the ECJ and refused the petition on three grounds. Firstly, that the issue was hypothetical as the UK Government had stated that they did not intend to revoke the notification. Secondly, that the matter interfered with parliamentary sovereignty and was outside the court’s jurisdiction. Thirdly, that the conditions for a reference had not been met, as the facts were not ascertainable and the issue was hypothetical.
The Petitioners' submissions
The Petitioners appealed the decision arguing that the issue was of great constitutional importance: Votes upon it were required in the Scottish, European and UK Parliaments. If a decision to remain was available as a matter of EU law, the UK Parliament could pursue that option irrespective of Government policy.
The Secretary of State for Exiting the European Union (as Respondent), argued that there was no real prospect of the Government seeking to revoke the notification and so there was simply no need to resolve any legal uncertainty.
The Court's decision
The court agreed with the Petitioners that it was neither academic nor premature to ask the ECJ whether the notification was capable of being withdrawn and for the UK to remain in the EU.
Lord Carloway, Scotland’s most senior judge and Lord President of the Court of Session concluded:
"It is clear, in terms of the European Union (Withdrawal) Act 2018, that MPs will be required to vote on whether to ratify any agreement between the UK Government and the EU Council. If no other proposal is proffered, a vote against ratification will result in the UK’s departure from the EU on 29 March 2019; a date which is looming up."
"It seems neither academic nor premature to ask whether it is legally competent to revoke the notification and thus to remain in the EU. The matter is uncertain in that it is the subject of a dispute; as this litigation perhaps demonstrates. The answer will have the effect of clarifying the options open to MPs in the lead up to what is now an inevitable vote."
While the Secretary of State's view that there was no realistic possibility of the notification being withdrawn was noted, the Court confirmed that the Government's declared position could not be binding as a matter of law.
Lord Drummond Young (concurring with Lord Carloway) said:
"If no agreement can be reached, the default option at present appears to be withdrawal from the European Union without any sort of agreement. The legal consequences of such a move would clearly be immense, and viewed from a professional legal perspective they would appear to be very hard to predict."
The issue of whether the Article 50 notification can be revoked unilaterally will now be decided by the ECJ, with the verdict expected by Christmas.
Why is the Court's decision so significant?
The Court's decision to refer the issue to the ECJ is probably the most fundamental legal development in the Brexit process since the High Court ruled that Parliament had to legislate before the Government could invoke Article 50.
It means that Parliament should have clear guidance from the ECJ as to the precise powers available to MPs when they are asked to vote on the Brexit deal.
In a statement following the Court's decision, a Government spokesman said:
“We are disappointed by the decision of the Court. We are giving it careful consideration. But as the Government has repeatedly said, we are committed to implementing the result of the referendum and will not be revoking Article 50.”
Implications of the ECJ's decision
A ruling by the ECJ on this point will be of both legal and practical significance.
While the Petitioners have welcomed the court's decision to refer the revocation decision to the ECJ, there is of course a risk that the ECJ finds the UK cannot revoke the notice it has given under Article 50. If so, it means that we will exit the EU regardless of any vote by the UK parliament or any second referendum.