TORY ministers are reportedly plotting how they could undermine the authority of the UK’s highest court if it decides to back Scotland’s Brexit legislation later this month.

The course of action – described as “the nuclear option” – is being drawn up ahead of a legal contest between the UK and Scottish governments over the EU Continuity Bill, passed in Holyrood earlier this year.

The legislation was introduced by ministers in Edinburgh following concerns the two administrations would not resolve a dispute on the transfer of devolved powers from Brussels in Westminster’s EU Withdrawal Bill.

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The UK Government is challenging the legality of the Scottish bill with the case due to be heard in the Supreme Court in London on July 24 and 2. Its judgment is due to delivered at the earliest in October.

If the UK side wins, the Holyrood bill will be struck down. But if the Scottish Government wins, according a BBC report, “legal sources in the UK Government” are looking at ways to ensure the Westminster legislation could still stand anyway – over-riding Scotland’s.

David Porter, the BBC’s Westminster correspondent, told the Good Morning Scotland radio programme yesterday: “If [the Supreme Court] sides with the Scottish Government, then potentially you have two Brexit bills covering the same areas from different parliaments.

“There are some in legal circles in the UK Government who said this wouldn’t work and that Westminster basically would have to flex it constitutional muscles and look to strike down the Holyrood legislation.

“People have said to me that if the UK Government was to go ahead with the powers it has in the Scotland Act to strike down the piece of legislation which was brought in by Holyrood and supported by Holyrood that is in effect the nuclear option. It would have huge political repercussions and those who have talked about a constitutional crisis for once would probably be correct in using that term.”

Porter suggested discussions were ongoing in the UK Government about pursuing such a controversial course of action. Some figures favoured pushing ahead to defeat the Scottish Government in the event it won the legal case, while others cautioned against.

Scottish Secretary David Mundell said the UK Government would act in accordance with the court’s decision”. He said: “The UK Government is not considering that as an option. We are going to the Supreme Court to seek its view on the position of the Continuity Bill.

“The Presiding officer of Scottish Parliament gave one view on the bill, the Lord Advocate another. It will be for the court to determine which view is the appropriate one.

“We will act in accordance with the judgment of the Court; we will not be repealing the bill from Westminster. “

A Scottish Government source said: “The UK Government should be concentrating on working with the Scottish Government and Parliament – not against us.

“It should think very carefully before trying to over-ride the majority wishes of Holyrood and of the UK Supreme Court – it is high-handed, arrogant behaviour like that which could see the Tories paying a very high political price in Scotland.”

Seven Supreme Court justices will preside over the case: Lady Hale, Lord Reed, Lord Kerr, Lord Sumption, Lord Carnwath, Lord Hodge, Lord Lloyd-Jones.