The Scottish and Welsh governments will be able to intervene in a historic legal battle over the UK's decision to split from the EU, the Supreme Court announced on Friday (18 November).

The move means lawyers from the devolved governments, led by the SNP and Welsh Labour, will able to address the top court as the UK government attempts to overturn a ruling from the High Court

"Counsel for the Scottish Government and for the Independent Workers Union of Great Britain have been invited to address in their skeleton arguments the relevance of points of Scots Law, so far as they do not also form part of the law of England and Wales, to the determination of the present proceedings," a spokesman for the Supreme Court said.

The High Court decided MPs must have a vote on the triggering of Article 50, the official mechanism to split from the EU, after the government unsuccessfully argued ministers held the legal power to do so.

The case was bought by investment fund manager and Remain voter Gina Miller. The businesswoman told IBTimes UK that she had faced a "deluge of hatred and anger" from Brexit supporters before and after the verdict.

"I cannot think of a better way to use my resources than to do what I believe to be right in preserving our democracy for everyone in the United Kingdom," she said.

The Supreme Court hearing will start from 5 December, with a final decision expected in January 2016. Interim Ukip leader Nigel Farage has promised to stage a 100,000-strong rally outside the court.

The demonstration is being organised by Leave.EU, the pro-Brexit campaign co-founded by insurance tycoon and Ukip donor Arron Banks.

"This will remind the Government, politicians and the establishment, including the court, that they cannot ignore the democratic vote of the people in the referendum," a Leave.EU source told The Daily Telegraph.

Shadow Chancellor John McDonnell caused controversy on 15 November when he revealed Labour would not oppose a vote on Article 50 if the House of Commons is given a say.

"To do so would put us against the majority will of the British people and on the side of certain corporate elites, who have always had the British people at the back of the queue," he said.

"The question of what Brexit means will be fought in the months and years through the negotiations and in the next election when we will define what a post-Brexit Britain looks like. It is time we all were more positive about Brexit, Labour wants to see an ambitious Brexit Britain."

A UK government spokesperson said: "It is a matter for the Supreme Court which applications to intervene are accepted. The UK government's position remains the same, and we will be taking strong legal arguments to court next month."