Te Pāti Māori co-leader Rawiri Waititi may have breached Parliament's rules by making comments about court proceedings.
During Question Time in Parliament on Wednesday, Waititi raised a supplementary question, referring to a matter before the courts.
ACT leader David Seymour responded, saying Waititi had "speculated that a particular individual has name suppression and is guilty of heinous crimes - both of those are in contempt of court and due to the long tradition of comity between this House and the courts, to make such statements are deeply disorderly, bring the House into disrepute, and should face very severe consequences".
"I can't believe, frankly, what I've just heard - the tikanga of this house is well known and should be respected."
Speaker Adrian Rurawhe said he would go back and "look at everything that's happened in Question Time today".
"I'd like everyone to calm down, thank you," he said. "I have ... allowed questions, supplementary questions to be asked - including [by] the the member himself on this very question today that have been out of order - almost completely out of order."
There are two rules in Parliament's Standing Orders - 116 and 418 (y) - which may be at issue.
Standing Order 116 says: "Matters awaiting or under adjudication in, or suppressed by an order of, any New Zealand court may not be referred to in any motion, debate, or question, including a supplementary question, subject always to the discretion of the Speaker and to the right of the House to legislate on any matter or to consider delegated legislation."
Standing Order 418 (y) lists "knowingly making reference to a matter that is suppressed by an order of a New Zealand court, contrary to the Standing Orders, in any proceedings of the House or of a committee" as an example of contempt of the House.
Rurawhe said Seymour had a "very clear procedure" open to him "if he wishes to take that course of action" - likely referring to an MPs ability to make a formal complaint.
"Raising it as a point of order in such instance is not appropriate," Rurawhe said.
If the Speaker receives the complaint and finds there may be a matter of privilege, he could then refer it to Parliament's Privileges Committee.
Waititi's interjection had followed a question from Seymour to Prime Minister Chris Hipkins. Seymour had faced criticism over comments he made last week about sending Guy Fawkes - the infamous man who attempted to blow up the British Houses of Parliament - to the Ministry for Pacific Peoples.
Seymour has maintained his comments were a joke about the ministry's spending after the Public Service Commissioner rebuked it for a nearly $40,000 spend on a farewell for its departing chief executive. ACT has long had a policy to abolish the ministry along with other departments like the Human Rights Commission.
He has refused to apologise or back down over the comments, and asked Hipkins during Question Time whether he stood by comments that politicians "have a particular duty of care to ensure that the statements we make don't inflame tensions".
"If he really believes that, why did he mischaracterise my criticism of wasteful spending at a government department as an attack on an entire ethnic group?"
Hipkins said it was for Seymour to clarify what he meant and why he thought his Guy Fawke's comment was appropriate.
"Mr Speaker, I know the member seems to want to turn the election campaign into a culture war with himself at the centre of it. We're actually focused on more important issues on the side of the House," Hipkins said.
"... I'm sure that the parties opposite will be getting more scrutiny, including uncovering the fact that the member himself has been propped up by a bunch of anti vaxxers," he said, referring to controversy over one current and two former ACT candidates.