Nicola Sturgeon's five steps to an independence referendum, explained

But the path to a second vote taking place is unlikely to be as straightforward as in 2014, thanks to opposition from the UK Government.

Here we look at plans Nicola Sturgeon has outlined to allow the people of Scotland to “express their views in a legal constitutional referendum” and the potential hurdles along the way.

Asking for a Section 30 order

The UK and Scottish Governments should agree a Section 30 order as the “democratic way to proceed” and put the legal basis of a referendum “beyond any doubt”, Sturgeon said.

This was the route taken in 2014, which allowed the necessary powers to be transferred to Scotland to hold an independence referendum.

The First Minister wrote to Boris Johnson on Tuesday to make it clear she is “ready and willing” to negotiate the terms of a Section 30.

However, with Johnson repeatedly making clear he is unwilling to do so, this is likely to be more of a formality than to succeed.

READ MORE: Tell us what you think about Nicola Sturgeon's route-map to indyref2

Legislation for the vote

The Scottish Government published the Scottish Independence Referendum Bill on Tuesday.

This sets out key aspects of the vote – including the date and the question to be asked on the ballot paper will remain as it did in 2014 – “Should Scotland be an independent country?”

The vote will be consultative and a majority Yes vote would not automatically lead to independence – as legislation would subsequently have to be passed by the Scottish and UK Parliaments.

Sturgeon said the idea that a consultative referendum would not have the same status as the vote in 2014 was “simply wrong, factually and legally”.

She said it would be exactly the same as the devolution referendum in 1997, the 2014 independence vote, and the 2016 Brexit referendum.

Referral to the Supreme Court

So if a Section 30 order is refused, what happens next?

Sturgeon said she will “never allow Scottish democracy to be a prisoner of Boris Johnson or any Prime Minister”.

The First Minister said it was crucial the lawfulness – or otherwise – of the referendum is established as a matter of fact, otherwise doubts would continue to be cast on the validity of the vote.

The legislative competence of Holyrood to pass the bill without a section 30 order is “contested”, she noted.

And so if the Scottish Parliament tried to do so, it would end up in court – facing a lengthy challenge from the UK Government or private individuals.

READ MORE: Independence: Boris Johnson's stance 'Kafkaesque', says ex Westminster official

Sturgeon said she had asked Lord Advocate Dorothy Bain, the Scottish Government’s most senior law officer, to exercise her power to refer the matter to the UK Supreme Court.

That process is underway, with the UK Government being served the relevant paperwork and the case filed with the court.

It remains to be seen if the court will look at the case – and if so, how long it will take and what it will decide.

“By asking the Lord Advocate to refer the matter to the court now, rather than wait for others to do so, we are seeking to deliver clarity and legal certainty in a timely manner and without the delay and continued doubt that others would prefer,” Sturgeon added.

Holyrood powers 

If the court does take the view Holyrood does have the power to hold a referendum, there will be “no doubt whatsoever that the referendum is lawful”, Sturgeon said.

The next step for the Scottish Government will then be to introduce the independence bill to Holyrood for it to be passed in time for the vote to proceed on October 19, 2023.

However, the court could also make decision that the Scottish Parliament does not have the power to hold a referendum.

“To be clear, if that happens, it will be the fault of Westminster legislation, not the court,” Sturgeon added.

She said it would clarify that “any notion of the UK as a voluntary union of nations is a fiction” and that “Westminster will always have the final say”.

“There would be few stronger or more powerful arguments for independence than that,” she added.

A “de-facto” referendum

Even if there is no lawful way for Holyrood to hold a referendum and the UK Government is still denying a Section 30 order, the First Minister said that would not be the end of it.

She said the SNP would fight the next General Election on the question of independence – and it would be a “de facto” referendum to ensure Scotland does have its say.