The Government has today lost a major case in the High Court on the issue of whether a Parliamentary vote is required before the Government issues notice under Article 50 of the Treaty on the Functioning of the European Union to the EU that the UK is leaving.

If the High Court’s decision stands, it means that the Government cannot begin the formal legal process of leaving the EU without there first being a vote in Parliament.

The full High Court judgment is available here. The decision turns on upholding the constitutionally sacrosanct principle of Parliamentary sovereignty:

This subordination of the Crown (i.e. the executive government) to law is the foundation of the rule of law in the United Kingdom. It has its roots well before the war between Crown and Parliament in the seventeenth century but was decisively confirmed in the settlement arrived at with the Glorious Revolution in 1688 and has been recognised ever since.

At the time of writing, the Government had indicated it would appeal. The High Court granted the Government a certificate which would enable the case to go straight to the Supreme Court. Permission will inevitably be granted and the hearing will no doubt be expedited. There is a rumour the hearing will be in early December, when there is a gap in sittings, with all 11 Justices hearing the case.

Number 10: disappointed, will appeal pic.twitter.com/j0wEBERFHe

— Faisal Islam (@faisalislam) November 3, 2016

There is a distinct possibility the Supreme Court will want to establish whether Article 50 can be reversed or revoked in the period between notice being given and a Member State actually formally legally leaving the EU. The two parties in the High Court agreed that it could not and the High Court accepted that as an underlying assumption, but the Supreme Court might well want to dig deeper. If so, it is highly likely that a reference would be made to the Court of Justice of the European Union on this question of EU law. The prospect of the EU court deciding on an issue around the UK leaving will leave some newspaper columnists foaming at the mouth.

Readers of Free Movement will be particularly interested in the impact, if any, this all has on the rights of EU nationals and their family members in the UK. As has repeatedly been said here, EU law continues to apply in the UK unless or until the UK formally leaves the EU. The formal legal process of leaving has not even begun yet, but Prime Minister Theresa May has stated that she intends to begin the process in by the end of March 2017. This would be when Article 50 would be triggered. Unless an agreement was reached first, the UK would then formally leave the EU two years later and EU law woud cease to apply then.

If the outcome of the court case stands (i.e. the Government does not actually appeal or does appeal but loses) then Parliament will have to have a vote before Article 50 is triggered.

What are the chances of MPs and Lords voting to trigger Article 50? That is a big question. It would be extraordinary for Parliament not to accept the result of the referendum and not permit Article 50 to be triggered. However, Parliament might well have something to say about the conditions or process of triggering Article 50.

In constitutional and democratic terms, the point of the challenge is that the Executive should not be given a completely free hand to make all decisions on what settlement the UK reaches with the EU without any oversight or input from the Legislature.

Jolyon Maugham QC, who was responsible for organising the Article 50 case, thinks there is a case for Parliament to require as a condition for the trigger of Article 50 that a clear choice on what Brexit actually means either to Parliament or to the people in a second referendum. So far, the Brexiteers and Leave campaigners have managed to get away with compeltely fudging key issues. Some Leavers said it means more immigration, some said less. Some Leavers said it means leaving the Single Market and the customs union, others said that the UK should remain in the European Economic Area, like Norway.

If the public, either directly in another plebiscite or through their elected delegates, our Members of Parliament, are presented with a choice of Hard Brexit or No Brexit, it is possible the country might vote for No Brexit. Alternatively, the knowledge that there is no Parliamentary majority for Hard Brexit might well force the Government to take a different path and pursue a Soft Brexit strategy of leaving the EU but remaining in the EEA or similar.