The judicial review proceedings will argue that the new checks on goods moving from Great Britain to Northern Ireland were imposed without the consent of the public.
Ms Foster is joined by DUP deputy leader Nigel Dodds, the party’s Westminster leader Sir Jeffrey Donaldson and chief whip Sammy Wilson, as well as former Brexit Party MEP Ben Habib, Eurosceptic peer Kate Hoey and Jim Allister, the leader of the Traditional Unionist Voice party.
She said: “Fundamental to the Act of Union is unfettered trade throughout the UK.
“At the core of the Belfast Agreement was the principle of consent yet the Northern Ireland protocol has driven a coach and horses through both the Act of Union and the Belfast Agreement.
“Neither the Northern Ireland assembly, the Northern Ireland executive nor the people of Northern Ireland consented to the protocol being put in place or the flow of goods from GB to NI being impeded by checks. They certainly did not consent to the arrangements for those checks being determined by a power over which we have no democratic say.”
Ms Foster said the judicial review was part of a “five-point plan of opposition” which also seeks to challenge the protocol in Westminster and Stormont.
That campaign includes a boycott of north-south ministerial engagement on issues related to the contentious trading arrangements.
Ms Foster also launched a petition calling for the triggering of Article 16 of the NI protocol and “remove any impediment or barrier to unfettered trade within the United Kingdom”. The debate on the issue is due to take place at Westminster on Monday.
The Northern Ireland protocol is designed to ensure there is no hard border in Ireland and effectively moved the regulatory and customs border to the Irish Sea, with a series of checks, certifications, inspections and declarations now required on many goods being shipped into the region from Great Britain.
Nationalists and the Irish government are committed to retaining it, while the EU has accused the UK of failing to observe the agreement properly.
SDLP leader and Foyle MP Colum Eastwood said: “The DUP’s legal action against the Ireland protocol is ill-judged and will only further entrench the febrile political environment as well as creating further uncertainty for people and businesses.
“There will be few with sympathy for the argument that the protocol, which prevents a hard border in Ireland and guarantees dual market access for local businesses, breaches the Good Friday Agreement.”
Micheal Martin, the Irish prime minister, has urged the DUP to put politics aside to find a practical resolution to problems after Brexit. He pointed out that the DUP was previously happy to work with the protocol on a practical level, “although they didn’t agree with it”.
Additional reporting by Press Association
