www.bbc.co.uk/news/uk-politics-38027230
The Scottish and Welsh governments are to be allowed to intervene in the Supreme Court battle over how Brexit should be triggered.
The government's appeal against the High Court ruling that MPs must vote on triggering Brexit will be heard in the Supreme Court from 5 December.
It will last four days, with the decision expected in the new year.
Theresa May has said she is "clear" she expects to start talks on leaving the EU as planned by the end of March.
Counsel for the Scottish Government is being invited by the Supreme Court justices to address the court on the relevance of points of Scots law, so far as they do not form part of the law of England and Wales.
Three senior High Court judges ruled that the prime minister does not have power to use the royal prerogative to trigger Article 50 of the Lisbon Treaty to start the two-year process of negotiating Brexit without the prior authority of Parliament.
Mrs May and her ministers are now asking the Supreme Court to overturn that unanimous decision.
Labour has said it will not attempt to delay or scupper this process if a vote goes ahead but pressure is mounting on the government from the devolved legislatures.
The Independent Workers Union of Great Britain, which describes itself as "fighting for the rights and welfare of some of the most vulnerable and under-represented workers in the UK", has also been given permission to make submissions to the court.
The Attorney General for Northern Ireland has made a reference to the court on devolution issues and did not need permission to intervene.
The historic legal challenge over Brexit was brought by investment fund manager and philanthropist Gina Miller and Deir Dos Santos, a hairdresser, with other "concerned citizens".
After Lord Toulson's retirement this summer, the appeal will be heard by all 11 remaining Supreme Court justices, led by their President Lord Neuberger.
At the completion of legal submissions, the justices will reserve their decision to a date "probably in the new year", a spokesman for the court said.