In short, something needs to happen to break the deadlock between the Scottish and UK governments on independence.

The first minister wants to hold a fresh vote, has a pro-independence majority at Holyrood and indeed has named a date. But successive prime ministers have insisted that “now is not the time”.

This means a transfer of power like the one which underpinned the 2014 vote is not forthcoming, and thus minds at Holyrood are turning to whether MSPs could just pass a referendum bill without Westminster’s blessing.

The UK government could challenge any bill passed by MSPs as potentially being outwith Holyrood’s powers, so Ms Sturgeon has opted to short-cut that argument.

Her government’s chief legal adviser – the Lord Advocate – has used her powers to refer the issue to the Supreme Court so that judges can settle the question once and for all.

Helpfully, the matter of MSPs legislating for a referendum has been kicking around for years – without ever being resolved – so the core arguments are fairly well-known.

The Scotland Act states that it would be outwith Holyrood’s competence to make provisions which “relate to reserved matters” – the reserved matter in question here being the Union of the Kingdoms of Scotland and England.

It may seem silly to ponder whether an independence referendum bill relates to the Union. How could it not? However, there are a number of technical points to dive into here.

There is a school of thought that the bare fact of holding a referendum seeking people’s views about independence would not in itself actually break up the union.

Nicola Sturgeon argued on Tuesday that the referendum would be “consultative, not self-executing” – explaining that this meant that “a majority yes vote in this referendum will not in and of itself make Scotland independent”.

Legislation would need to be passed at Westminster and Holyrood to actually make independence a reality – and thus technically, in pure legal terms, the act of asking the electorate about it is a separate issue.

Ms Sturgeon points to the Brexit referendum as an example. The 2016 vote didn’t drop the UK out of the EU instantaneously, but rather sparked the years of negotiations and legislative wrangling which resulted in a rather gradual break-up.

Some have also pointed to the Brexit court case brought by Gina Miller in 2017, where judges opined that the 2016 referendum “did not change the law in a way which would allow ministers to withdraw the UK from the EU without legislation”.

They said the effect of the referendum was “of great political significance” and was “in no way devoid of effect”, but that “unless and until acted on by parliament, its force is political rather than legal”.

There is a nod to this argument in the first paragraph of the bill published alongside Ms Sturgeon’s statement. It specifically says the purpose of the bill is to “ascertain the views of the people of Scotland on whether Scotland should be an independent country”.

This is what Ms Sturgeon means when she says it would be a “consultative” vote – but she says the same was true of those in 2014 and 2016.

They may also make arguments about the right of Scots to seek self-determination under various statutes – the kitchen sink tends to be thrown in these legal submissions – but this is the core point about competence.

The UK government’s position is that the constitution is clearly reserved.

This is loose language legally, given the UK does not have a written constitution and the Scotland Act specifically reserves the Union itself.

But it is broadly the point UK law officers will pursue – that Westminster is the sovereign parliament, and that it has reserved the powers in this area. Holyrood’s powers, meanwhile, are specifically limited within the confines of the Scotland Act.

In fact they advanced these very lines of argument recently in response to a citizen legal challenge at the Court of Session in 2021. That case was ultimately thrown out as being “premature”, but provided a reasonable insight into some of the arguments we may hear.

The UK government side argued that by law, in order to “relate to” a reserved matter, a Holyrood bill must have “more than a loose or consequential connection” with it – and that a referendum bill would clearly meet this test.

They said that even beyond legal effect, legislation authorising a referendum would “seek to build momentum towards achieving independence” and the breakup of the UK.

They also argued that Scotland leaving the UK would impact directly on the powers of the UK parliament – something MSPs are also not meant to do.

And they cited statements made by ministers during the passage of the Scotland Act in 1998 – including Scottish Secretary and future first minister Donald Dewar’s claim that “a referendum that purported to be ultra vires [beyond Holyrood’s powers] is in itself ultra vires”.

It would be foolish to speculate about how the judges will assess these arguments, for all there has been some academic chin-stroking about how they have viewed the Scotland Act and devolved competence in previous cases.

The current president of the court, Lord Reed, and his deputy Lord Hodge, are both Scottish and indeed former Court of Session judges. They will be well versed in the matter of devolution, and have stressed the paramount importance of judicial independence and impartiality.

In any case, the result of the case is not guaranteed to settle whether or not there is a vote in October 2023.

For example, should the Scottish government lose, they are not going to pack up and go home. In fact they have threatened to double down by treating the next general election as a “de facto referendum”.

And equally, should the pro-union side lose, it wouldn’t necessarily stop them arguing that this is not the best time for a referendum. It would put tremendous pressure on them, but they could argue that just because you can have a vote doesn’t mean you should.

That pressure is really the point here. Ms Sturgeon still really wants to win an agreement with the UK government.

Her goal, of a legitimate referendum that wins international recognition and can actually deliver independence, is best served by a gold-standard process with both sides taking part in good faith.

So no matter what the result is in court, the search for a political solution is likely to continue.