The Supreme Court has unanimously ruled that Brexit’s Northern Ireland Protocol is lawful.
The legality of the contentious trading arrangements was challenged at the UK’s highest court by a collective of unionists and Brexiteers.
The original appellants, including former Stormont first ministers Arlene Foster and the late David Trimble, had argued the arrangements were unlawful.
But the challenge was rejected by a panel of five justices on Wednesday, following a two-day hearing last year.
It had previously also been dismissed by the High Court and Court of Appeal in Belfast.
Announcing the Supreme Court’s decision, Lord Stephens said the appeal was “unanimously dismissed” on all grounds.
The protocol, which is a key aspect of the Brexit Withdrawal Agreement, was jointly designed by London and Brussels to keep Ireland’s land border free-flowing following the UK’s departure from the EU.
Becoming effective in 2021, the arrangements instead shifted customs and regulatory checks to the Irish Sea and created new red tape on the movement of goods between Great Britain and Northern Ireland, with trade in the region remaining subject to certain EU Single Market rules.
Many unionists in Northern Ireland are vociferously opposed to the protocol, claiming it has undermined the region’s place within the United Kingdom.
The DUP is currently blocking the functioning of the devolved powersharing institutions at Stormont in protest over the Irish Sea trade barriers.
The Supreme Court ruling came as the EU and UK continue to engage in intensive negotiations aimed at agreeing ways to cut protocol bureaucracy.
The appellants in the case argued that legislation passed at Westminster to give effect to the Brexit Withdrawal Agreement conflicts with the 1800 Acts of Union that formed the United Kingdom, particularly Article 6 of that statute guaranteeing unfettered trade within the UK.
Concurring with the decisions of the lower courts, the Supreme Court found that while Art 6 of the Acts of Union has been “modified” by the Protocol, that was done with the express will of a sovereign parliament and so therefore was lawful.
Lord Stephens said: “The most fundamental rule of UK constitutional law is that Parliament, or more precisely the Crown in Parliament, is sovereign and that legislation enacted by Parliament is supreme.
“A clear answer has been expressly provided by Parliament in relation to any conflict between the protocol and the rights in the trade limb of article VI (of the Acts of Union 1800).”
Justice Stephens said that Art 6 of the Acts of Union had not been repealed.
“The modification of article VI of the Acts of Union does not amount to a repeal of that article,” he said.
“The Acts of Union and article VI remain on the statute book but are modified to the extent and for the period during which the Protocol applies.”
The appellants also contended that the protocol undermines the peace process legislation underpinning Northern Ireland’s powersharing settlement at Stormont – the 1998 Northern Ireland Act.
The Northern Ireland Act, which gave effect to the historic Good Friday peace agreement, guarantees that the constitutional status of the region can only be changed with the consent of its citizens via referendum.
Dismissing this ground of challenge, the Supreme Court said the Northern Ireland Act only regulates one specific aspect of the region’s constitutional status – namely, whether it remains within the UK or becomes part of a united Ireland.
Lord Stephens said this issue had already been ruled on by the Supreme Court in the first challenge brought by Gina Miller over whether Parliament had to legislate to withdraw from the EU.
He said there was no reason to depart from that earlier ruling and the court accordingly rejected the contention that the Act regulated other potential constitutional changes in Northern Ireland, such as those the appellants claim have been brought about by the protocol.
The third ground of challenge related to the cross-community provisions within the Northern Ireland Act (Section 42) that provide a mechanism to ensure that controversial decisions at Stormont can only be passed if they are supported by a certain proportion of both nationalist and unionist MLAs in the Assembly.
The Withdrawal Agreement does provide for a future Assembly vote on the continuation of the protocol; however, the UK Government passed regulations that amended Stormont rules so the vote can be passed on a straight majority basis, rather than having to meet the cross-community consent thresholds.
The appellants challenged the lawfulness of those regulations.
The Supreme Court found that protocol legislation passed by Parliament had lawfully modified the NI Act to allow for the “consent resolution” vote on the trading arrangements to be carried out by way of straight majority.
The judges therefore said there was no incompatibility between the regulations and the Act as amended.
In 2021, Belfast High Court judge Mr Justice Colton dismissed the original judicial review challenge against the lawfulness of the protocol on all grounds.
His judgment was upheld by the Court of Appeal last year.
The Court of Appeal later granted leave for the case to be referred to the Supreme Court.
The case involved two conjoined challenges – one taken by unionist politicians and Brexiteers including Traditional Unionist Voice (TUV) leader Jim Allister, former Brexit Party MEP Ben Habib and Baroness Kate Hoey, and the other mounted by a loyalist pastor from Belfast, Clifford Peeples.