A Wellington City Council committee has voted in favour of compulsory microchipping for all cats over 12 weeks old after a fiery debate, amid threats of possible legal action.
The amendment passed by 10 votes to three at a turbulent meeting of the council's environmental committee today.
Proponents of the idea say it is good for the environment, and a foolproof way of distinguishing between domestic cats, and ferals and strays.
But those opposed say it stretches the council's legal powers - and are warning they will test it in court.
The amendment, which would take full effect from 2018, still has to be approved by the full council at a meeting in two weeks.
The discussion descended into shouting matches between councillors on several occasions, with Helene Ritchie strongly objecting to the effectiveness of microchipping as an environmental measure.
Another councillor opposed to the amendment, Jo Coughlin, said she was concerned by how quickly it was passed.
"I do feel like it has been rammed through a bit. I have spoken previously about the benefits of microchipping, I've had personally a great experience with that, but whether I actually feel at this point that we should be making it mandatory for all, at a cost which we don't know enough about, I'm not sure."
It costs between $40 and $80 to microchip a cat.
Simon Woolf, who introduced the amendment, said people formed deep emotional connections with their animals.
"This allows us to identify our pets, as opposed to cats that are feral and stray," he said. "Let's just do this. Let's lead, let's not be risk-averse to this, and let's provide some absolutely necessary leadership".
Ray Ahipene-Mercer said efforts to preserve Wellington's natural wildlife had been admirable and successful, and microchipping fell within the committee's remit.
"We go on about bringing people to the city to see this, to see that, to see the birds and everything else," he said.
"But here is a mechanism which will enable us to better manage the issues to do with the killing of wildlife."
Ultimately, the committee voted to accept the amendment by 10 votes to three, with dissenting votes cast by Ms Coughlan, Ms Ritchie, and Nicola Young.
Legal opinions sought
The Feline Rights group, and other backers, said before the vote that the council had sought legal advice on what it could do with cats found on reserve land - and said this was proof the council wanted to set up cat kill zones.
High-profile lawyer Mai Chen had provided the group with a legal opinion on whether the council could make microchipping mandatory.
The opinion said the council's evidence for microchipping cats was insufficient, that it did not have the power to make bylaws to protect wildlife, that it had pre-determined what law it wanted and pre-emptively written off a voluntary approach.
There was also not enough proof the bylaw would fix the problems it aimed to address.
One of the other people behind that was Kent Duston, who was Wellington Mayor Celia Wade-Brown's campaign manager in 2010 and an advisor in 2013.
He said the council's processes were dodgy and if compulsory microchipping was part of the final bylaw, he would seek a judicial review.
He believed the council was acting beyond the Local Government Act.
Ms Chen's advice appeared to be in conflict with the council's own legal advice.
A legal opinion from DLA Piper said the council was allowed to regulate cats for the purpose of protecting wildlife, and if cats were found on reserve land and could not be identified, they could be seized, sold or destroyed, it said.