The Scottish government cannot hold an independence referendum without the UK government’s consent, the Supreme Court has ruled.
First Minister Nicola Sturgeon wants to hold a referendum on 19 October next year.
But the court ruled unanimously that she does not have the power to do so because the issue is reserved to Westminster.
The UK government has refused to grant formal consent for a referendum.
Court president Lord Reed said the laws that created the devolved Scottish Parliament in 1999 meant it did not have power over areas of the constitution including the union between Scotland and England.
These issues are the responsibility of the UK Parliament, he said, and in absence of an agreement between the two governments the Scottish Parliament is therefore unable to legislate for a referendum.
He also rejected the Scottish government’s argument that any referendum would simply be “advisory” and would have no legal effect on the union, with people only being asked to give their opinion on whether or not Scotland should become an independent country.
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Lord Reed said: “A lawfully held referendum would have important political consequences relating to the union and the United Kingdom Parliament.
“Its outcome would possess the authority, in a constitution and political culture founded upon democracy, of a democratic expression of the view of the Scottish electorate.
“It is therefore clear that the proposed Bill has more than a loose or consequential connection with the reserved matters of the Union of Scotland and England, and the sovereignty of the United Kingdom Parliament.”
Responding to the outcome, Ms Sturgeon said she was disappointed but respected the ruling of the court, and stressed that the judges do not make the law and only interpret it.
She added: “That is a hard pill for any supporter of independence, and surely indeed for any supporter of democracy, to swallow.”
The first minister told a media conference that a referendum remained her preferred option, but in the absence of an agreement the SNP would use the next UK general election as a “de facto referendum” in an attempt to demonstrate that a majority of people in Scotland support independence.
The “precise detail” of how this would work will now be a matter for the party to debate, she said, with a special conference to be held in the new year.
Ms Sturgeon said: “We must and we will find another democratic, lawful means for Scottish people to express their will” and accused the UK government of “democracy denial”.
A series of pro-independence rallies are being held in towns and cities across Scotland on Wednesday evening.
Recent opinion polls have suggested that the country is essentially split down the middle on the independence question, but with a very narrow majority in favour of staying in the UK.
However the SNP and Greens form a pro-independence majority in the Scottish Parliament.
Prime Minister Rishi Sunak welcomed the “clear and definitive ruling” from the Supreme Court.
Speaking at Prime Minister’s Questions, he said: “The people of Scotland want us to be working on fixing the major challenges that we collectively face, whether that’s the economy, supporting the NHS or indeed supporting Ukraine.
“Now is the time for politicians to work together and that’s what this government will do.”
Downing Street later said Mr Sunak will seek to avoid another referendum while he is prime minister.
His press secretary told reporters: “I think that would be something that we would look to do.”
She added that there had been a “once-in-a-generation referendum not too long ago and that result should be respected”.