The Northern Ireland Protocol is “unlawful on a number of grounds”, a court considering a challenge brought by unionists to its legality has heard.
A judicial review on the protocol, part of the Brexit deal which creates a trade border between the North and Britain, has begun at the High Court in Belfast.
Launching the challenge on Friday, John Larkin QC said the judge, Mr Justice Colton, would be asked to take a view on the legality of the protocol.
He told the court: “It’s not about the decision way back when to make the protocol, it is asking Your Lordship to accept that the protocol is unlawful on a number of grounds and therefore it’s unlawful to try and give effect to it.”
He added: “The regulations are incompatible with the Act of Union in providing for the continuation of the protocol, which is itself incompatible with the Union.”
Mr Larkin also referred to an affidavit from Jim Allister, one of a number of unionist politicians who has brought the legal challenge.
He said: “He makes the point the Act of Union cannot be disregarded, bypassed or misapplied.
“The UK created by these Acts, he says, and the place of Northern Ireland is fundamentally changed.”
The judicial review is being taken in the name of unionists from across the UK, including DUP leader Arlene Foster, UUP leader Steve Aiken, TUV leader Jim Allister and the North's former first minister Lord David Trimble.
In a statement ahead of the hearing, the applicants said they aim to “undo the great wrong” done by the UK in the imposition of the protocol.
“It is not just trade and economic prosperity but the constitutional integrity of the United Kingdom that requires defeat of the Union-dismantling protocol,” they said.
“The purpose of this Judicial Review challenge is to undo the great wrong which was done in the imposition, without consent, of arrangements which leave Northern Ireland as a rule taker of foreign laws – over which we have no control, the United Kingdom partitioned down the Irish Sea and trade fettered disastrously with our biggest market.
“All this we believe infringes our constitutional and economic entitlements under the Acts of Union and the assurances of the Belfast Agreement, as well as our basic democratic entitlement to be governed only by laws made by those we elect.
“We are grateful to our legal team under the leadership of John Larkin QC who have marshalled compelling arguments which we look forward to being expounded over the next few days.”
They also thanked those who contributed to a crowd-funding campaign for the challenge.
“We may be the named applicants but we take this action on behalf of all who care about democracy, our economy, the future of the United Kingdom and basic fairness,” they added.