Advocate General for Scotland, Lord Stewart QC, published his written submission on behalf of UK ministers on Wednesday.
It argues the case on whether a prospective bill, which would legislate for another referendum, would be within the powers of Holyrood.
But the case, brought forward by Scotland’s Lord Advocate, Dorothy Bain, “does not fall within the jurisdiction” of the Supreme Court, according to UK law officers.
The UK Government’s clear view remains that a Bill legislating for a referendum on independence would be outside the legislative competence of the Scottish Parliament
UK Government spokesperson
Lord Stewart went on to advise the court to “decline to determine the reference as a matter of its inherent discretion”.
However, he also argues that even if the court does decide it has jurisdiction over the matter, Holyrood would be unable to hold a lawful referendum.
Scotland’s First Minister, Nicola Sturgeon, has stated she intends to hold a referendum on October 19 2023, depending on the court’s ruling.
Lord Stewart QC said: “A referendum on Scottish independence plainly (at least) relates to the reserved matters of the United Kingdom of Scotland and England and of the Parliament of the United Kingdom.
“That conclusion is unaffected by whether the referendum is, in its outcome, advisory or legally binding.”
A UK Government spokesperson said: “People across Scotland want both their Governments to be working together on the issues that matter to them and their families, not talking about another independence referendum.”
The spokesperson added: “On the question of legislative competence, the UK Government’s clear view remains that a Bill legislating for a referendum on independence would be outside the legislative competence of the Scottish Parliament.”
The UK Government’s submission also states that there are “surprising consequences” which could arise by the Lord Advocate’s referral to the court.
Were the outcome to favour independence, it would be used to seek to build momentum towards achieving that end: the termination of the Union and the secession of Scotland
Lord Stewart, Lord Advocate of Scotland
It said it could allow UK law officers to make “pre-emptive” references to any Scottish legislative proposal deemed to be “outside of legislative competence”.
In its submission to the court, submitted last month, the Scottish Government leaned heavily on any future referendum not being “self-executing”, meaning it would be purely advisory and only meant as a way to ascertain the views of the Scottish people.
But Lord Stewart QC said it was wrong to consider the referendum as “advisory”.
If the decision favoured independence, he said it would be used to “build momentum” towards the “termination of the Union”.
His submission said: “It is, of course, right that the outcome of the referendum provided for by the draft Bill has no legal effect: it is not self-executing.
“But nor can it credibly be suggested that the outcome of the referendum will be advisory in the sense of being treated as a matter of academic interest only.”
It continued: “Were the outcome to favour independence, it would be used (and no doubt used by the SNP as the central plank) to seek to build momentum towards achieving that end: the termination of the Union and the secession of Scotland.
“It is precisely in that hope that the draft Bill is being proposed.”
The SNP have also made an attempt to intervene in the case, arguing that – as a public body – it would be “fair, just and reasonable” for the party to make arguments to the Court.
The hearings will be heard on October 11 and 12.