THE UK Supreme Court has granted the SNP permission to intervene in the case on Scotland's right to hold an independence referendum.

The party had applied to be allowed to submit its own arguments to the court in early August, despite the Scottish Government’s top law officer – Lord Advocate Dorothy Bain – already having submitted a case.

The UK Government has also submitted and published its own arguments in the indyref2 case.

On Wednesday, the Supreme Court said that the SNP would be allowed to intervene and submit a third written case – but it had to be limited to 20 pages and must avoid “repetition of the Lord Advocate’s arguments”.

The party will be given until September 21 to file its submission. The case is due to be heard on October 11 and 12.

The Supreme Court further said that the other parties in the case – Lord Advocate Bain and the UK Government’s top law officer for Scotland, Keith Stewart – would be allowed to submit a response to the SNP’s arguments.

Both the UK and Scottish governments’ top law officers will be given 14 days after the submission of the SNP’s argument to file their response.

The party had argued that if they were allowed to intervene in the case this would mostly be by written submission, but also asked the court to allow “short oral submissions to supplement" that. The Supreme Court's decision will restrict the SNP to written arguments only. 

The SNP’s deputy leader at Westminster, Kirsten Oswald, previously said that the party’s application to intervene was intended to “support and complement” the arguments for a referendum bill being within the Scottish Parliament’s competence.

It added: “The applicant is a person with an interest in these proceedings, standing its history, involvement, and prominence in UK politics on the matter of Scottish independence and, in particular, the rights of the Scottish people to self-determination.”

The party has been contacted for comment on the Supreme Court's acceptance of its arguments.

What arguments on indyref2 has the Supreme Court seen so far?

On June 28, the Scottish Government published its prospective referendum bill.

Nicola Sturgeon told MSPs that she had asked the Lord Advocate to submit it directly to the Supreme Court to decide if it fell within the Scottish Parliament's devolved powers. 

In July, Bain's arguments to the Supreme Court were published

In the 51-page document, the Lord Advocate (below) said Holyrood should be able to pass the legislation on indyref2 with the aim of finding out “the wishes of the people of Scotland on their future”.

The National: Lord Advocate Dorothy Bain QC could advise the Scottish Government that a referendum bill is potentially outside its competence

The QC adds that the motivations of the Scottish Government, or political parties, in passing the bill are “not legally relevant”.

“The legal consequences of the bill are, relevantly, nil," she wrote.

The holding of referendums is devolved to the Scottish Parliament, but matters which "relate to" the Union are reserved.

There is, as Bain said in her reference to the Supreme Court, a "genuine issue of law that is unresolved" – namely whether a consultative independence ballot could be said to relate to the Union, or if Holyrood could hold one without Westminster's consent. 

However, Bain further said that she did not have the "necessary degree of confidence” that Holyrood could legislate for a second independence referendum to clear a bill for introduction to the Scottish Parliament.

READ MORE: Win or lose, here's why Unionists don't want the Supreme Court ruling on indyref2

On the Unionist side, the UK Government's first move was to ask the Supreme Court to throw out Bain's submission and refuse to hear any arguments on Scotland's right to hold a second referendum. 

The Tory administration argued that a ruling would be "premature" given that the Scottish Government's referendum bill has not yet been submitted to, or passed by, Parliament.

However, this argument fell and the Supreme Court said it would allow the case to be heard.

In August, the UK Government's Advocate General for Scotland submitted papers which argued that the SNP’s proposed referendum bill related directly to reserved matters as set out in the Scotland Act.

It said: “The scope of the reservation is self-evident: it is the Union. It is not the dissolution of the Union: whether a referendum were to support or reject independence, it would equally relate to the Union. The way in which the question on the referendum is framed, neutral or otherwise, does not affect the connection to the reserved matter.”