Five judges will shape the course of the UK's future following crunch hearings this week which could pave the way for a fresh Scottish independence referendum.
Today Nicola Sturgeon confirmed that if a Supreme Court ruling goes her way, Scotland will go to the polls on October 19 next year.
Addressing the SNP faithful in Aberdeen today, the First Minister said : : "Over the next two days the Supreme Court will consider whether the current law allows the Scottish Parliament to legislate for an advisory referendum.
"If Westminster had any respect at all for Scottish democracy, this court hearing wouldn’t be necessary.
"But Westminster has no such respect. That means this issue was always destined to end up in court, sooner or later.
"Better, in my view, that it is sooner. If the Court decides in the way we hope it does, on 19 October next year, there will be an independence referendum."
She said that the party will "respect" the judgement if it goes against them, saying the SNP will take time to "reflect".
Here's how the crucial legal process will work.
What will the judges make a ruling on?
At the heart of the case is proposed legislation in the Scottish Parliament called the Scottish Independence Referendum Bill.
This would allow for a second vote on Scottish independence to take place next year.
However, there are questions over the legality of an independence referendum which does not have a section 30 order from Westminster - the legal instrument which can grant Holyrood the power to organise a vote.
The five judges have been asked to decide whether the Bill relates to "reserved matters" - meaning it is outwith Holyrood's competence.
How did this come to court?
When she published the Bill in June this year, Nicola Sturgeon said her opponents would cast doubts on its legitimacy.
The First Minister said she wanted an "indisputably lawful" referendum to take place and sought to head off any legal challenge by referring it to the Supreme Court herself.
This is why the case will be called a "reference" in the Supreme Court.
What will the UK Government argue?
Both sides have published some of their legal arguments in the months ahead of Tuesday's hearing.
The UK Government, under successive Prime Ministers, has always maintained opposition to a second independence referendum.
In August, the Advocate General asked the Supreme Court to "decline to determine the reference", saying it is outwith the court's jurisdiction.
However, he also argued that even if the court does decide it has jurisdiction over the matter, Holyrood would be unable to hold a lawful referendum.
A referendum plainly relates to rserved matters and is outside Holyrood's legislative competence, he argued.
The Scotland Act states that "the Union of the Kingdoms of Scotland and England" is a reserved matter.
What will the Scottish Government argue?
The Scottish Government's case has leaned heavily on the vote being "advisory" rather than "self-executing" and therefore has no real effect on the Union.
In a 51-page filing submitted in July, the Lord Advocate argued the Bill would simply be to "ascertain the wishes of the people of Scotland on their future".
She wrote: "The legal effects of the Bill would be limited to facilitating the holding of a referendum vote, identifying those eligible to vote, the timing of the vote and affirming that the Referendums (Scotland) Act 2020 would apply."
Who else is involved in the case?
The SNP has submitted its own legal argument to the Supreme Court, separate from the Scottish Government's.
The party was granted the chance to intervene in the case via a written submission.
This document stressed the right to self determination, stating that it must inform the interpretation of the Scotland Act 1998.
What if the Supreme Court rules against the Scottish Government?
Ms Sturgeon accepts that her legal case in the Supreme Court may not be successful.
If this is the case, she says it will not be the court's fault but rather that of Westminster legislation.
In this scenario, she says the SNP will fight the next general election on one issue: "Should Scotland be an independent country?"
The First Minister says this will make the next general election a "de facto referendum".
When might there be a vote?
If the Scottish Government is successful, Ms Sturgeon is proposing to hold the referendum on October 19, 2023.
This is within the SNP's timescale of holding the vote in the first half of the current session of the Scottish Parliament.
When will the Supreme Court decide?
The five judges listed are Lord Reed, Lord Lloyd-Jones, Lord Sales, Lord Stephens and Lady Rose.
While there is no set time for the judgment to be issued, it could be weeks or months away.
Lord Hope, a former deputy president of the Supreme Court, has suggested such a decision could take six to eight weeks.
