Winston Peters says he will seek a judicial review of Speaker Trevor Mallard's decision to trespass him from Parliament grounds.
"This is not about whether former members of Parliament should be treated differently to others who were at the protest – they should not," Peters said this morning.
"This is about fairness, freedoms, democracy, and one law for all New Zealanders," the former deputy prime minister added.
"It is my intention to seek a precedent on behalf of the hundreds of others who were unreasonably and therefore unlawfully trespassed for peacefully protesting."
Mallard said he had not received any legal papers from Peters.
He told the Herald he did not believe the trespass orders should be revoked but added: "I'm not going into any detail on something that could be before a court."
The Parliamentary Service Commission met yesterday to decide whether former MPs should be exempt from the trespass orders.
The commission comprised representatives from each party in Parliament. Apart from Act, all parties said former MPs should not be exempt.
Mallard said he had not believed former MPs should be exempted.
"We treated all people who trespassed the same. Anyone who trespassed got trespassed."
Prime Minister Jacinda Ardern told The Country on Newstalk ZB the trespass decision was ultimately one for the Speaker.
Ardern said she had suggested getting all the political parties together to discuss some related issues.
"I still think there's a bit of consideration to be given, perhaps, to some people who were obviously more involved than others. But ultimately, it is going to be his call."
The PM said she was not in charge of Parliament's grounds or Parliamentary Service.
"I do make sure that I keep that separation. It doesn't mean that I won't have a view," she said today.
"I've always tried to maintain a respectful relationship with party leaders generally."
Ardern said her philosophy in politics was "play the ball, not the man".
Act leader David Seymour said the trespass orders issued to people who simply visited the protest were petty and vindictive.
"The orders will only result in lengthy and costly legal battles and taxpayers will lose.
"The focus should be on those who were violent or there is reason to believe will cause trouble in the future.
"Sleeping dogs should have been left to lie instead of inflaming a situation that has already cost taxpayers millions."
Otago University law professor Andrew Geddis earlier today said Mallard was exercising general law in the issue of the trespass notices.
Geddis told Newstalk ZB the trespass notice had been issued for Parliament, so an extra layer was added stating it could only be used in a reasonable manner.
Geddis predicted Peters' lawyer would argue the decision to trespass was an unreasonable one, given Peters had a fairly low-level involvement in the protest.