The UK Supreme Court has ruled that Scotland does not have the power to hold a new referendum on independence without the consent of the British government, a judgment that is a setback for the Scottish government's campaign to break away from the United Kingdom.
The top court ruled the Scottish parliament "does not have the power to legislate for a referendum on Scottish independence".
Supreme Court President Robert Reed said the five justices were unanimous in the verdict, delivered six weeks after lawyers for the pro-independence Scottish administration and the Conservative UK government argued their cases at hearings in London.
Scottish First Minister Nicola Sturgeon said she was disappointed but would respect the judgment.
But, she said on Twitter: "A law that doesn't allow Scotland to choose our own future without Westminster consent exposes as myth any notion of the UK as a voluntary partnership & makes case for (independence)."
UK Minister for Scotland Alister Jack said the government respected the ruling and "we will continue to work constructively with the Scottish government in tackling all the challenges we share and face".
The semi-autonomous Scottish government wants to hold a referendum next October with the question "Should Scotland be an independent country?"
The UK government in London refuses to approve a vote, saying the question was settled in a 2014 referendum that saw Scottish voters reject independence by a margin of 55 per cent to 45 per cent.
The pro-independence government in Edinburgh wants to revisit the decision, arguing Britain's departure from the European Union, which most Scottish voters opposed, radically changed the political and economic landscape.
Sturgeon argues she has a democratic mandate to hold a new secession vote because there is an independence-supporting majority in the Scottish parliament.
During Supreme Court hearings last month, Dorothy Bain, the Scottish government's top law officer, said the majority of Scottish MPs had been elected on commitments to hold a fresh independence referendum.
She also said a referendum would be advisory, rather than legally binding.
UK government lawyer James Eadie argued that power to hold a referendum rested with the UK parliament because "it's of critical importance to the United Kingdom as a whole".
Polls suggest Scots are about evenly split on independence, and a majority of voters do not want a new referendum soon.
Scotland and England have been politically united since 1707. Scotland has had its own parliament and government since 1999 and makes its own policies on public health, education and other matters. The UK-wide government in London controls matters such as defence and fiscal policy.
Sturgeon had said that if her government lost the court case, she would make the next UK election a de facto plebiscite on ending Scotland's union with England.