Story presenter Heather du Plessis-Allan bought a rifle by mail order, in October, by putting fictitious details in a form, to demonstrate weaknesses in gun laws.
Police investigating her actions searched the Wellington apartment she shares with her journalist husband Barry Soper yesterday for examples of her handwriting.
Media commentator Bill Ralston, the former head of news at Television New Zealand, told Morning Report today that the raid raised serious concerns about the relationship between journalists and the police.
Ralston said it was a heavy-handed approach and police were "sending a very unsubtle message".
"I had a look at the search warrant that her husband Barry Soper received yesterday, and it didn't talk about gun charges as such. It talked about forgery and it talked about deception. Now those are very, very serious charges, and it just seems brutal to me."
Ralston said it appeared that the intent of the raid was to to send a message to journalists that if they went anywhere near the edges of the law, or insulted the New Zealand police, they would see a heavy response. He said it was not the first time police had targeted journalists, and pointed to the case of journalist and author Nicky Hager, who garnered police attention with his 2014 book Dirty Politics.
"If you go back to Nicky Hager's home being raided, whether you agree with [what] Nicky did or not, or what Heather did or not, there is a trend now where the police seem to be targeting journalists and going into their homes and searching for evidence. That just makes me very uncomfortable."
He said the police's priorities appeared to be trying to protect their image and reputation, as shown by the case of Jarrod Gilbert, a gang researcher who was briefly banned from accessing police data recently.
"Unfortunately they are doing it in a heavy-handed way, there was no need for that kind of police raid and search of her flat.
"It just seem to me they are deliberately making it as hard and as heavy as they can be to try and dissuade anyone from doing anything in connection with the police. Just ask Jarrod Gilbert, who only managed to get access to police material after a long fight via the media."
Ralston did concede that du Plessis-Allan had broken the law in obtaining the firearm.
"She did in theory break the law but she did it to show how easy it could be broken and showed how easily guns can be obtained.
"Frankly, the fact that they changed the procedures immediately indicates that she did them a favour telling them about part of their system that didn't work, and she did a favour for the rest of the country, so people aren't wandering around with firearms."
Police have defended the search of the apartment, saying it was part of a criminal probe into the alleged purchase of a firearm by deception.
Detective Inspector Chris Cahill of Auckland CIB said police were obligated to fully investigate the case, especially when it may have involve forgery or the impersonation of a police officer.
In a statement released later today, Auckland City District Commander Richard Chambers said they had made requests to speak to relevant staff at Mediaworks, which owns TV3, but were turned down.
Superintendent Chambers says the police then executed the search warrants to progress the investigation.
No charges have been laid against du Plessis-Allan.