Scotland’s First Minister Nicola Sturgeon has said she wants to have a second referendum on Scottish independence in October 2023.

However, the matter will be referred to the UK Supreme Court in order to establish legality of the legislation behind the vote.

The First Minister has already said there is an “indisputable” mandate for another vote after a majority of independence-supporting MSPs were returned in last year’s Holyrood elections.

Here are some of the key issues:

– What happened last time?

In 2014, Scots voted in favour of remaining in the United Kingdom by 55% to 45%.

Scottish independenceNicola Sturgeon is publishing a series of papers on independence (Russell Cheyne/PA)

– What has changed since then?

The key issue raised by supporters of independence is Brexit. During the 2014 campaign, those in the No campaign said Scotland would no longer be a member of the EU if it was independent.

But the 2016 referendum on membership of the bloc meant that happened regardless, angering independence supporters and increasing calls for another vote.

There has also been the Covid-19 pandemic, which strained relations between the Scottish and UK Governments on how best to handle it, with Scottish ministers saying they would be able to go further than the UK with the full powers of independence.

Westminster, however, highlighted the might of the British exchequer in being able to fund initiatives such as the furlough scheme.

– What does independence mean?

The Scottish Government is due to publish a series of documents which will set out details of their vision for an independent country, these have been referred to collectively as the independence prospectus.

Leaving the UK would grant Scotland powers it does not already have under the devolution settlement.

Currently, issues such as health and education are controlled by the Scottish Parliament in Edinburgh, while things like foreign policy and defence are reserved to Westminster.

If Scotland voted to be independent, it would control all areas of policy, but not everything will change immediately.

The position of the SNP – the largest independence supporting party – is that the Queen should remain head of state and the pound should remain the official currency, at least until a separate Scottish currency is launched.

However, the currency position could change when the paper is published in the coming months.

‘All Under One Banner’ rallyOpinion polls suggest Scots are split on the issue (Jane Barlow/PA)

– What would an independent Scotland look like?

That is hard to say, but the independence prospectus being published in the coming months should provide more detail.

In the foreword to the first document, Nicola Sturgeon said her aspiration was for a “wealthier, fairer and more successful country”.

– What needs to happen for a referendum to be held?

After months of speculation, Nicola Sturgeon has set out her response to questions over the legality of an independence referendum which does not have a section 30 order – the legal instrument which can grant Holyrood the power to organise a vote.

She has published a Scottish Independence Referendum Bill and referred it to the Supreme Court in order to ensure her plans are “indisputably lawful”.

The First Minister wants to head off any challenge by her opponents, who would argue that the Scottish Parliament does not have the power to arrange a vote without Westminster’s consent.

The Supreme Court is the UK’s highest court and has previously ruled on disputes between the UK and Scottish Governments.

– When might there be a vote?

The First Minister 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.

– What if the Supreme Court rules against the Scottish Government?

Nicola 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.

If this happens, 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”.

Scottish IndependenceNicola Sturgeon has accepted she may not win the Supreme Court case (Jane Barlow/PA)

– What do other Scottish parties think?

The Scottish Conservatives have said they will not take part in a “pretend poll”, saying a “potentially illegal” referendum is the wrong priority for Scotland.

They say it will distract from dealing with issues with the cost-of-living crisis and NHS waiting times.

Scottish Labour say the timing is wrong as people are still losing their lives due to Covid-19.

The Scottish Liberal Democrats are also opposed to the First Minister’s plans, however she has the support of the Scottish Green Party who have two ministers in her Government.

– What do the polls say? Opinion polls have generally shown Scots are split on the issue of independence.

A recent IpsosMori poll for STV found support for a Yes vote was at 50% and No at 50% when undecideds are removed.

There are also conflicting views on when such a vote should take place.

– What does the UK Government say?

Westminster, under two different prime ministers in recent years, has rejected calls for another vote.

Both Theresa May and Boris Johnson have said “now is not the time” for a referendum.

This sentiment was echoed by a spokeswoman for the UK Government following the announcement of the proposed date.

The UK Government says the constitution is reserved to Westminster, meaning Holyrood cannot organise a vote on its own.