A DATE has been set for a high-profile clash between London and Edinburgh over Holyrood’s powers.

The UK Supreme Court has scheduled a hearing for challenges raised by the UK Government’s law officers against two recent Scottish Parliament Bills. 

Five justices, including Lord Reed, the Scottish judge who is President of the Court, will hear the related cases on June 28 and 29.

The Bills both incorporate outside standards into Scots law - the United Nations Convention on the Rights of the Child (UNCRC) and European Charter of Local Self-Government.

The UNCRC Bill is intended to give enhanced legal protection to children by obliging public bodies to respect their rights and comply with UNCRC requirements.

MSPs passed both Bills unanimously in March but they have not received royal assent and so are not yet law because of the referral to the Supreme Court.

The UK Government argues they encroach on Westminster’s sovereign powers.

The Supreme Court could uphold the Bills as competent or send them back to Holyrood for amending.

The last Holyrood Bill referred to the Court was about Brexit in 2018.

The Court found it was largely competent when passed, but the referral and delay meant it was overtaken and rendered defunct by later Westminster legislation.

SNP ministers have called the latest referral “menacing” and a “blatant power grab” by London.

READ MORE: John Swinney accuses Westminster of 'power grab' over children's rights Bill

The UNCRC Bill was raised frequently by SNP politicians during the recent Holyrood election campaign, leading to a rare rebuke by the Dean of the Faculty of Advocates.

Roddy Dunlop QC said it was not "shameful", as the SNP claimed, for the UK Government to contest the Bill.

"No one queries the rights of children," he said.

"The question is the competence of Scottish Parliament.

"It’s a constitutional question, not a political one."

At FMQs on Thursday, Nicola Sturgeon said the UK Government had challenged the UNCRC Bill because it didn’t want its decisions “on things such as immigration to be subject to that kind of legal protection and scrutiny”.

However, as immigration is reserved, this would suggest the Bill is indeed straying beyond Holyrood’s powers. 

She also said it “illustrates, again, why we need more powers being taken out of the hands of the Tory Government at Westminster and put into the hands of this Government and this Parliament”.

A Supreme Court statement on the “facts” of the cases said the UK law officers “do not take issue” with Holyrood’s power to incorporate versions of the treaties into Scots law.

Rather, they were concerned that “both Bills would bestow upon the Scottish courts extensive powers to interpret and scrutinise primary legislation passed by the sovereign UK Parliament”.

As that would modify Section 28(7) of the Scotland Act 1998, the UK law officers considered parts of the Bills were therefore “outside the legislative competence of the Scottish Parliament”.

The UK law officers are also seeking the Court’s guidance on the correct reading of the Bills to ensure they are within Holyrood’s legislative competence, “if such a reading is possible”.

READ MORE: Nicola Sturgeon denies 'weaponising children's rights' to pick fight on constitution

The Court website said the Counsel General for Wales had also given notice of his intention to participate in the references as a relevant UK Law Officer.

The Lord Advocate, James Wolffe QC, was yesterday due to lodge a written case with the Court setting out the SNP Government’s position.

However he is unlikely to present arguments to the Court himself next month, as he is standing down imminently, making the case an early test for his successor. 

As the matter is currently before the Court, the Scottish Government declined to comment.