The 11 Supreme Court judges who ruled on UK's Brexit appeal
The government has lost its appeal against the High Court's ruling that Article 50 cannot be invoked without Parliament's support.
It was the first time, all 11 of the Supreme Court's permanent justices, including those from Northern Ireland and Scotland, presided over a case, but who are they?
Supreme Court president Lord Neuberger
Lord Neuberger, 68, is the president of the Supreme Court, a position he has held since 2012, and is the UK's most senior judge.
After studying chemistry at Oxford University he worked at the merchant bank N M Rothschild & Sons from 1970-1973 until he was called to the Bar in 1974.
In 2013 he voiced fears about legal aid cuts, telling the BBC they could lead people to "take the law into their own hands".
Lord Neuberger has also led an investigation for the Bar Council, which regulates barristers, into widening access to the profession.
He has two sons and one daughter.
Deputy president Lady Hale
Lady Hale, 71, is deputy president of the Supreme Court and in October 2009 became the first woman justice of the Supreme Court when the court was established, replacing the Law Lords.
Lady Hale, who became deputy president in June 2013 and is the UK's most senior female judge, previously said she was "disappointed" no other woman had reached the level she had.
In January 2004, she became the UK's first woman Law Lord after a varied career as an academic lawyer, law reformer and judge.
In October 2013 she told the BBC: ""I am disappointed that in the 10 years since I was appointed [a Law Lord] not one among the 13 subsequent appointments to this court has been a woman.
"Now things are improving in the lower ranks of the judiciary, but regrettably not yet up here."
She has one daughter and lists her hobbies in Who's Who as "domesticity", drama and duplicate bridge.
Lord Mance, 73, was one of an original group of nine that were appointed as justices of the Supreme Court when it was established in October 2009.
He had previously been a Lord Justice of Appeal and, before that, a High Court judge.
Lord Mance has one son and two daughters and his hobbies, according to Who's Who, include tennis, languages, music and walking.
Lord Kerr, 68, served as Lord Chief Justice of Northern Ireland from 2004 to 2009, and was the last Law Lord appointed before the creation of the Supreme Court.
He was called to the Bar of Northern Ireland in 1970, and to the Bar of England and Wales at Gray's Inn in 1974.
Lord Kerr has two sons and lists his hobbies in Who's Who as "trying to be (and hoping to make my family) happy".
Lord Clarke, 73, spent 27 years at the bar, specialising in maritime and commercial law, undertaking a wide variety of cases in these areas.
He became a Recorder in 1985, sitting in both criminal and civil courts.
In 2005, he was appointed Master of the Rolls and Head of Civil Justice and in October 2009 he became a justice in the Supreme Court.
He has one son and two daughters.
Lord Wilson, 71, became a justice of the Supreme Court in May 2011 after working for most of his career in the field of family law.
He argued in favour of gay marriage, telling Queen's University in Belfast that he wondered how long Northern Ireland would "be able to hold back the tide in favour of same-sex marriages".
Speaking in 2014, he said that that to allow same-sex couples the right to marry strengthened rather than weakened marriage.
Northern Ireland is the only country in the UK where same-sex marriage is not legal.
He has one son and a daughter.
Lord Sumption, 67, became a justice of the Supreme Court in January 2012,
He has been described as having a "brain the size of a planet" and the "cleverest man in England".
In a BBC interview in 2010, he denied these nicknames were true, saying "I don't know where these phrases come from. There are lots of clever people around. I'll admit to being one of them, but that's all."
He has two daughters and one son and his hobbies, according to Who's Who, include music and history. He has written several history books, including The Hundred Years' War, volumes one, two three and four.
Lord Reed, 60, is one of the two Scottish justices of the Supreme Court.
He served as a senior judge in Scotland for 13 years, being appointed to the Outer House of the Court of Session in 1998 and promoted to the Inner House in January 2008 before he was made a justice in the Supreme Court in February 2012.
Lord Reed also sat as an ad-hoc judge of the European Court of Human Rights. He has two daughters, and lists his main hobby in Who's Who as music.
Lord Carnwath, 71, served as Attorney General to the Prince of Wales from 1988 to 1994.
He was a judge of the Chancery Division from 1994 to 2002, during which time he was also chairman of the Law Commission.
Lord Carnwath was appointed to the Supreme Court in April 2012.
His hobbies, as listed in Who's Who, include playing the viola, singing (Bach Choir), tennis and golf.
Lord Hughes, 68, became a Queen's Counsel in 1990 and was later appointed a High Court judge.
He was appointed as a justice of the Supreme Court in April 2013.
Lord Hughes, who has one son and a daughter, lists his hobbies in Who's Who as garden labouring, mechanics and bellringing.
Lord Hodge, 63, joined the Supreme Court in October 2013 and is one of the two Scottish justices.
He has two sons and a daughter and he lists his hobbies in Who's Who as opera and skiing.