An emergency legal bid to prevent a Stormont vote on continuing post-Brexit trading arrangements for Northern Ireland is to be heard the day before the planned Assembly debate.

The challenge taken by loyalist activist Jamie Bryson against Northern Ireland Secretary Hilary Benn has been listed for a leave hearing on Monday afternoon.

Mr Bryson is challenging Mr Benn’s move to initiate the democratic consent process that is required under the UK and EU’s Windsor Framework deal.

The vote on extending the current trading arrangements is due to take place in the Northern Ireland Assembly on December 10.

It is understood Mr Bryson intends to represent himself when the matter is heard before a judicial review judge on Monday.

Mr Bryson had threatened to seek the emergency judicial review if Mr Benn did not respond by Thursday confirming that he is stopping the democratic consent process.

With the Northern Ireland Secretary making clear that the vote will proceed as scheduled, stressing that the process is now the responsibility of the devolved Assembly, Mr Bryson has secured the hearing date at Belfast High Court on Monday at 2pm.

The activist’s argument is grounded on law changes introduced by the previous UK government earlier this year as part of its Safeguarding the Union deal to restore powersharing at Stormont.

He claims that if the amendments achieved their purpose – namely, to safeguard Northern Ireland’s place within the United Kingdom – then it would be unlawful to renew and extend post-Brexit trading arrangements that have created economic barriers between the region and the rest of the UK.

In 2023, the UK Supreme Court unanimously ruled that the trading arrangements for Northern Ireland are lawful.

The appellants in the case argued that legislation passed at Westminster to give effect to the Brexit Withdrawal Agreement conflicted with the 1800 Acts of Union that formed the United Kingdom, particularly article six of that statute guaranteeing unfettered trade within the UK.

The Supreme Court found that while article six of the Acts of Union has been “modified” by the arrangements, that was done with the express will of a sovereign parliament, and so therefore was lawful.

Mr Bryson contends that amendments made to the Withdrawal Agreement earlier this year – as part of the Safeguarding the Union measures proposed by the Government to convince the DUP to return to powersharing – purport to reassert and reinforce Northern Ireland’s constitutional status in light of the Supreme Court judgment.

The framework, and its predecessor the Northern Ireland Protocol, require checks and customs paperwork on goods moving from Great Britain into Northern Ireland.

Under the arrangements, which were designed to ensure no hardening of the Irish land border post-Brexit, Northern Ireland continues to follow many EU trade and customs rules.

This has proved highly controversial, with unionists arguing the system threatens Northern Ireland’s place in the United Kingdom.

Advocates of the arrangements argue they help insulate the region from negative economic consequences of Brexit.

A dispute over the so-called Irish Sea border led to the collapse of the Northern Ireland Assembly in 2022, when the DUP withdrew then first minister Paul Givan from the coalition executive. The impasse lasted two years and ended in January when the Government published its Safeguarding the Union measures.

Under the terms of the framework, a Stormont vote must be held on articles five to 10 of the Windsor Framework, which underpin the EU trade laws in force in Northern Ireland, before they expire.

The vote must take place before December 17.

Based on the numbers in the Assembly, MLAs are expected to back the continuation of the measures for another four years, even though unionists are set to oppose the move.

DUP leader Gavin Robinson has already made clear his party will be voting against continuing the operation of the Windsor Framework.

Unlike other votes on contentious issues at Stormont, the motion does not require cross-community support to pass.

If it is voted through with a simple majority, the arrangements are extended for four years. In that event, the Government is obliged to hold an independent review of how the framework is working.

If it wins cross-community support – which is a majority of unionists and a majority of nationalists – then it is extended for eight years.

The chances of it securing such cross-community backing are highly unlikely.

Speaking to reporters in Dublin earlier this week, Northern Ireland Secretary Mr Benn said “the vote will go ahead because it’s provided for in the legislation”.

He said: “I started the process as required by writing to the Speaker and the motion has now been tabled.

“It is a decision for the Assembly to make whether they wish articles five to 10 of the Windsor Framework to continue in place. We wait to see the result and then we will act accordingly again in accordance to the legislation.”