The question of whether the Scottish Parliament can unilaterally declare a second referendum on independence will be heard at the UK Supreme Court from today.
The case concerns proposed legislation at the Scottish Parliament called the Scottish Independence Referendum Bill.
Nicola Sturgeon says an independence vote could be held as soon as next October.
Judges have been asked to decide whether the Bill relates to “reserved matters” – meaning it is the responsibility of Westminster, not Holyrood.
Ms Sturgeon asked the Lord Advocate, Scotland’s chief law officer, to refer the Bill to the Supreme Court when she published the legislation in June.
This was in order to head off any legal challenge from her opponents, with the prime minister saying she wanted an “indisputably lawful” referendum to take place.
The UK government, represented in the court by the Advocate General, is opposed to a second referendum.
The Advocate General has argued in written submissions that a referendum plainly relates to reserved matters and is outside Holyrood’s legislative competence.
He has also asked the court to rule on whether it has jurisdiction to hear the case, saying the Bill has not yet been introduced to the Scottish Parliament.
At the weekend, the prime minister spoke to journalists about the upcoming case while attending the SNP conference in Aberdeen.
Asked if she was confident the Supreme Court will grant Holyrood the ability to hold a second referendum, Ms Sturgeon said: “I am very hopeful and optimistic of that.
“But anybody who knows anything about court hearings would know that there’s not a lot of point trying to second-guess a court or speculate about the court’s outcome.”
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