Judges have been urged to finally resolve the "festering issue" of whether Holyrood has the legal power to hold a referendum on independence without Westminster approval.
The Supreme Court in London met today to hear arguments for and against Nicola Sturgeon's plan to hold an IndyRef2 next year.
But Scots were warned by judge Lord Reed it could take "some months" before a judgement is published as more than 8,000 legal papers must be examined.
The First Minister asked her top law officer, Lord Advocate Dorothy Bain, to refer the case to the court as a way of unblocking the constitutional log-jam.
The SNP leader claims her party has a clear mandate to ask Scots for the second time if they want to breakaway from the UK - but Boris Johnson and his successor Liz Truss have repeatedly disagreed.
In her opening statement to the court, Bain argued it was in "the public interest" for judges to issue a ruling on the case.
She explained that a majority of Scottish MPs were elected in 2019, and MSPs in 2021, on manifesto commitments to hold a further referendum.
"The issue of Scottish independence is a live and significant one in Scottish electoral politics and the Scottish Government wish to introduce a bill in the Scottish Parliament to provide for the holding of a referendum," she said.
She told a panel of five judges the question of whether the Scottish Parliament has the legal powers to hold an independence referendum has been contested since "the advent of devolution".
And she agreed with an earlier observation from former lord advocate that this has become a "festering issue" that required resolution.
The Lord Advocate went to argue the Scottish Parliament was not constrained when it was consulting the views of the Scottish people.
She pointed to various examples of the Scottish Parliament debating and passing motions on matters reserved to Westminster.
Bain said: "Scottish ministers, it can be argued, are not precluded from consulting the people of Scotland on a wide variety of issues,
"And they are not precluded to consult with the people of Scotland on the issue of independence."
Lawyers acting for the UK Government argued that all constitutional matters are clearly reserved to Westminster and the case should be dismissed.
James Eadie KC said the court was being asked to rule on a draft bill that has yet to be introduced to the Scottish Parliament.
He insisted it should not rule on legislation until the precise terms are known.
Eadie claimed it was not appropriate for courts to "deal with abstract questions of law, when the facts are not known".
The hearing will continue on Wednesday before judges retire to consider their written verdict.
Nicola Sturgeon has said her party "will respect the judgement" no matter what decision is reached.
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