Supreme Court hears further evidence in Brexit challenge case

He is urging the panel, headed by the court's president Lord Neuberger, to overturn a ruling against the Government by the High Court on November 3.

The Lord Chief Justice Lord Thomas and two other judges decided that British Prime Minister Theresa May lacked power to use the royal prerogative to trigger Article 50 of the Lisbon Treaty and start the two-year process of negotiating Brexit without the prior authority of Parliament.

In a case of "great constitutional importance", the Supreme Court has heard a claim that it is for the British Government to exercise prerogative powers in the conduct of the UK's affairs on the international plane.

Long before the start of the second day of the appeal on Tuesday, members of the public joined a lengthy queue in the hope of getting a place inside the court to witness the proceedings.

The case, which will finish on Thursday with a judgment reserved until the new year, has attracted worldwide attention.

As well as hearing further submissions from Mr Eadie, the judges will start to hear argument this afternoon on behalf of Gina Miller, an investment fund manager and philanthropist, who was the lead claimant in the successful High Court judicial review action.

The justices are also set to hear from other parties, including Northern Ireland and the Welsh and Scottish Governments.

The justices have emphasised that the appeal concerns an issue of law, and is not about the wider political questions surrounding the UK's departure from the EU.

Mr Eadie told the court the idea that Parliament would not be involved in the Article 50 triggering of Brexit "cannot possibly be sustained" and said opposition motions were due to be debated in the British House of Commons this week. Parliament would also be involved in subsequent questions of legislation.

Lord Neuberger suggested to Mr Eadie that "Parliament will be involved if it wants to be". He suggested if it wanted to debate the whole question of Article 50 notice being served under prerogative powers "that is something they can do".

Mr Eadie agreed, saying: "Parliament can look after itself."

He was echoing a key submission made earlier to the court by Attorney General Jeremy Wright.

Mr Eadie, in concluding remarks, told the justices: "It is said that the Government giving Article 50 notice is an affront to Parliamentary sovereignty because Parliament has created rights and only it can alter them,

"Our case fully respects, and offers no affront, to Parliamentary sovereignty."

The QC said: "Parliament is already deeply involved, and unsurprisingly involved, in the whole process of withdrawal."

Mr Eadie said there had already been debate - and an opposition debate set down for Wednesday - and no party in Parliament had "called for parliamentary legislation to be enacted in advance of the giving of notice".

He added: "Parliament does not seem to want the obligation the Divisional Court (High Court) has thrust upon them."

The QC told the court: "Article 50 merely starts the process. It effects in itself no change in the law, and negotiation will be needed. The outcome can't be known.

"The aim will be to seek agreement. The negotiations will no doubt be long and arduous."

He added: "Parliament will inevitably be involved in that process of withdrawal."

Mr Eadie said the British Government would "address policy area by policy area" to see "what the brave new world should look like".

He argued that the "apparent simplicity" of the case put forward by those challenging the British Government's use of the prerogative "represents, we submit, a serious constitutional trap".

If the Supreme Court ruled against the British Government, then the "courts would be imposing, in effect, a new control of the most serious kind in a highly controversial, and by Parliament, a carefully considered, area", he said.