Legal challenges against the lawfulness of Brexit’s Northern Ireland Protocol have been dismissed by a High Court judge in Belfast.

Mr Justice Colton rejected arguments that the contentious post-Brexit trading arrangements breached the terms of the 1800 Acts of Union and the 1998 legislation that underpins the Good Friday Peace Agreement.

In a lengthy judgment, the judge agreed with the applicants’ contention that the Brexit Withdrawal Act, in which the Protocol is enshrined, conflicted with the 1800 Acts of Union.

But he ruled that both were constitutional legislation and said that the Withdrawal Act, which was expressly agreed by Parliament, effectively overrode the provisions of the 200-year old law.

The judge also dismissed the arguments put forward by the applicants that the Protocol breaches key provisions of the 1998 Northern Ireland Act, in particular related to the consent mechanisms contained in the law that flowed from the historic peace deal of 23 years ago.

He ruled the Protocol did not breach articles 1 and 42 of the Act.

The judge also refused the judicial review ground that Northern Ireland citizens’ human rights are being breached by being unable to influence the EU laws that apply in the region, by not being able to elect MEPs to the European Parliament.

He also rejected the argument that the terms of the Northern Ireland Protocol breach EU law.

The lead judicial review case was pursued in the names of unionists and Brexiteers from across the UK, including former DUP leader Arlene Foster, former UUP leader Steve Aiken, TUV leader Jim Allister, Belfast Agreement architect Lord Trimble, former Brexit Party MEP Ben Habib and Baroness Hoey.

An adjoined case was taken by Belfast pastor Clifford Peeples.

Both were dismissed by the judge in Belfast on Wednesday.

The Protocol is deeply unpopular with unionist and loyalists in Northern Ireland as it creates a trade border between the region and Great Britain and means EU rules governing trade in goods still apply in Northern Ireland.

A key plank of the legal case before the High Court hinged on the contention that Article 6 of the Acts of Unions, which enshrines that no part of the United Kingdom should be treating differently to the rest in respect of trade access, has been breached by the Protocol.

Significantly, Mr Justice Colton determined that the Acts of Union and the Brexit withdrawal legislation were both laws of a constitutional character.

He said his role was therefore to rule on which one should prevail in law.

The judge said a starting point, based on fundamental legal principles, was that the most recent legislation should take precedence.

“Much constitutional water has passed under the bridge since the enactment of the Act of Union,” he said, noting that Ireland had been partitioned since that law was passed.

The judge said there was no legal precedent whereby the Acts of Union had operated to “nullify a subsequent act of Parliament”.

He said there was however capacity within the UK’s constitutional arrangements for the “implied repeal” of statute with the passing of latter laws.

Concluding on that issue, he said: “The Acts (2018 and 2020 Withdrawal Agreement Acts) have been approved and implemented pursuant to the express will of Parliament and any tension with Article Six of the Act of Union should be resolved in favour of the agreement acts of 2018 and 2020.”

Outside court, Mr Allister confirmed the ruling would be appealed, with a case potentially set for the Supreme Court.

“This battle is far from over because we refuse to accept that the Union is over, which is the message of the Protocol,” he said outside Belfast High Court.

Baroness Hoey added: “We are committed to carrying this on because I think today’s judgment really has shown that the people of Northern Ireland need to wake up to the fact that the Union now has been broken and that we are going to have to fight back.

“So can I thank everybody in Northern Ireland who has given us support and make it absolutely clear that this is only the beginning of the legal challenge and also of people’s protests against what has been done to us without our consent.”

Mr Habib said Prime Minister Boris Johnson had to act.

“The judge found against us on every ground but, crucially, what he found was the Act of Union Article 6, a fundamental part of the Act of Union 1800, no longer exists, that Northern Ireland and Great Britain have effectively been severed by the Protocol,” he said.

“It seems to have just gone through Parliament without even the Prime Minister recognising that his own act, the Northern Ireland Protocol, has actually broken the union of the United Kingdom.

“He denied it in the Commons the other day but actually that’s precisely what this High Court has just ruled, the union of the United Kingdom has been broken.”

He added: “The only positive that you might put on it (the court ruling) is we do now officially know that the union of the United Kingdom has been trampled on by the Protocol, that the union has been broken.

“At least that now is out in the open, that’s out in the open.

“The Prime Minister has to face up to the reality that his own judicial system has said that the union of the United Kingdom has been broken and he has to grapple with it, he needs to put that right.”