Scottish independence: Will there be a second referendum?
The UK Supreme Court has ruled that the Scottish government cannot hold an independence referendum without the Westminster government's consent.
First Minister Nicola Sturgeon had said she wanted a vote to take place on 19 October 2023.
What has the Supreme Court said?
The court's president, Lord Reed, said the laws that created the Scottish Parliament in 1999 meant it did not have the power to legislate on areas of the constitution - including the union between Scotland and England.
The court rejected the Scottish government's argument that any referendum would be "advisory", and would have no legal effect.
Lord Reed said that in the absence of an agreement between the two governments, the Scottish Parliament does not have the power to legislate for a referendum.
Hasn't Scotland already had an independence referendum?
Yes, in September 2014, when Scottish voters were given the choice of staying in the UK or becoming an independent country.
They backed staying the UK by 55% to 45%.
Why is independence back in the spotlight?
In truth, it has never really gone away.
Ms Sturgeon called for another referendum - "indyref2" - immediately after the UK as a whole voted to leave the EU in the 2016 Brexit referendum. Scottish voters backed remain by 62% by 38%.
Independence supporters argued that Scotland should take its future into its own hands, and no longer be tied to the UK and its Conservative government.
Since then Ms Sturgeon has made repeated attempts to push for another vote but there has been no agreement with the UK government.
The SNP currently has a pro-independence majority in the devolved parliament alongside the Scottish Greens. It argues that its electoral success - coupled with the Brexit vote - mean it has a "cast-iron mandate" to hold another referendum.
But the UK government insists it will not grant formal consent for a referendum through what is known as a Section 30 order.
This was put in place ahead of the 2014 referendum. Many - but not all - experts believe such a mechanism would be needed again to ensure any future vote is legal.
Ms Sturgeon wrote to the then Prime Minister Boris Johnson in July asking for a similar agreement this time, but he said no.
Will indyref2 happen?
The UK government argues that the 2014 referendum was, in Ms Sturgeon's own words at the time, a once-in-a-generation opportunity.
Former Prime Minister Boris Johnson previously suggested that meant another one shouldn't be held for about 40 years, with Rishi Sunak - the current incumbent of No 10 - also opposed to a vote.
The UK government has accused the SNP of failing to give clear answers to key questions on issues such as currency and pensions in an independent Scotland. It also warns that any attempt by Scotland to rejoin the EU would lead to a hard border between the two countries.
Ministers also say Ms Sturgeon and her government should be focusing on recovery from the Covid pandemic and improving public services like health and education.
The first minister has already started publishing a series of papers setting out the case to break away from the UK.
They argue that an independent Scotland could be "wealthier, happier and fairer", and that people should have the right to choose how they are governed.
So what is Ms Sturgeon's plan now?
The first minister says she "stands ready" to reach an agreement with the UK government on a referendum, but expects the UK government will continue with its "democracy denial".
"The SNP is not abandoning the referendum route. Westminster is blocking it," she said.
Ms Sturgeon's intention is to make the next UK election a "de facto referendum", with the SNP standing on the single issue of independence.
The first minister wants the SNP to hold a special party conference next year to agree the details of this plan.
In the meantime, she said the party would launch a major campaign "in defence of Scottish democracy".
Would Scots vote for independence?
Polling expert Prof Sir John Curtice says the last half dozen polls have - on average - put support for independence at 49%, with 51% against, once "don't know" votes are excluded.
This suggests that the country hasn't seen the big surge in support for independence that Ms Sturgeon hoped for in the wake of Brexit, the Covid pandemic and Boris Johnson becoming prime minister.
But with such a slender lead in the polls, the pro-UK side also cannot be confident of victory, and will be mindful of how support for independence increased before the last referendum.
However, polling has also suggested that there are fewer undecided voters now than there were at the start of the last referendum campaign, so it may be harder for either side to win people over.
Dr Emily Gray, head of polling at Ipsos Scotland, said it was clear that the issue of Scottish independence was not going away.
She said pro-independence parties would see the Supreme Court ruling as "another unfair block in the way of Scottish democracy".
But she added that Nicola Sturgeon would also face questions about making the next general election a single issue vote on independence:
"When we've polled on this recently, the only route that a clear majority sees as legitimate is a referendum that both the Scottish government and the UK have agreed to."