GREEN Party leader Steven Agnew is among several plaintiffs taking a case on Brexit through the courts in Dublin.
The case seeks a referral to the European Court of Justice to clarify if triggering Article 50 can be reversed by the British government without requiring consent from all other 27 member states.
Lawyers for the British government have said that, once started, the process is irrevocable, but some EU leaders say the UK can change its mind.
The crowd-funded legal challenge is being brought by London tax lawyer Jolyon Maugham and Mr Agnew is among several green politicians supporting the case as plaintiffs.
Mr Agnew said the case was not about opposing the referendum result, but instead "providing a safety net as the UK takes the giant leap of leaving the EU".
"I am involved in this case to represent the interests of the people of Northern Ireland. The majority of people here voted to Remain in the EU and their voice should be heard," he said.
"This is not a case primarily directed against the Republic of Ireland, it is a democratic means by which to ensure that the UK comes to the best possible outcome.
"It's apparent that Brexit will be bad for Northern Ireland. Our former First Minister Arlene Foster has gone AWOL while Northern Ireland's interests have slipped well down the prime minister's agenda."
British prime minister Theresa May plans to invoke Article 50 in March, triggering two years of formal EU divorce talks.
