Police Minister Stuart Nash is under fire for saying he previously rang the Police Commissioner about appealing a court judgement.
But he denies he has interfered in police matters and he says he wasn't the Police Minister at the time.
"I phoned up the Police Commissioner and said surely you're going to appeal this," Nash told Newstalk ZB early on Wednesday morning.
"I don't know if you remember when we were doing the firearms stuff, I was wandering around telling everyone that if you have an illegal firearm, you can face up to five years in jail.
"This bloke didn't have a license, had illegal firearms, illegal ammunition and had guns without a licence, and got home detention. I think that was a terrible decision by the judge. Judges need to read the room on this."
Speaking to media later, Nash said he hadn't been interfering and stands by it being a "bad decision".
He said he asked the Commissioner whether he would consider appealing the case.
Nash said he wasn't the Police Minister at the time and didn't follow up with the Commissioner about the case. He couldn't provide a date for when the phone call happened.
Nash was re-appointed Police Minister this year after previously being Police Minister last term.
"I am not interfering in any way shape or form," Nash said.
"I wasn't the Minister of Police, I was chewing the fat with a guy who was a mate about a decision that I thought was very bad in the circumstances that I had been involved in when I was the Minister of Police and buying back firearms and I'm going to leave it at that."
Nash said the Police Commissioner is a "very enabled, very smart man who can make his own decisions".
"When he gets a mate calling him, questioning about the veracity of a case, it's up to him to determine."
Nash's comments stunned the ACT Party.
"The Police Minister of all people should know that police independence is paramount. We do not want to live in a country where politicians get involved in police prosecution decisions," ACT leader David Seymour said.
"It wouldn't be the first time if a Minister in this Government distanced themselves from an issue saying 'of course we have to respect the independence of police operations.'"
Seymour asked: "How on earth does [Nash] think such political interference in prosecutions is acceptable?"
The Cabinet Manual says: "Following a long-established principle, Ministers do not comment on or involve themselves in the investigation of offences or the decision as to whether a person should be prosecuted, or on what charge".
Section 16 of the Policing Act says: "The Commissioner is not responsible to, and must act independently of, any Minister of the Crown."
In the Newstalk ZB interview, Nash went on to say that society is "sick to death of these gang members creating havoc".
"We want it dealt with appropriately but unfortunately, police don't determine what happens to them once they get in court."
The ACT leader made the comparison to former National minister Maurice Williamson, who resigned his ministerial post in 2014 after contacting police about an investigation into a businessman.
Then-Prime Minister Sir John Key said Williamson assured him he didn't intend to influence the police investigation, but Williamson's decision to discuss the investigation with police "was a significant error of judgement".
"The independence of Police investigations is a fundamental part of our country's legal framework," Sir John said at the time. "Mr Williamson's actions have been very unwise as they have the potential to bring that independence into question."
David Cunliffe, the Labour leader at that time, said that was a "very serious" matter.
"New Zealanders must have an assurance that Ministers in any Government will not, cannot, and must not use their positions either to favour some members of the community or to apply pressure to independent organisations like the Police."
Seymour said Nash's actions are "far worse" than Williamson's.
"Number one, he is the Police Minister, who is responsible for securing Police funding in the Budget. He carries far more sway with Police than any other MP. Number two, while Mr Williamson's actions and motivations were highly questionable, Stuart Nash is not hiding the fact that he attempts to influence police prosecutions, in fact he's boasting about it on prime-time radio!"