Many are pointing to reports going back decades looking at the drivers of crime and gang membership, and calling for an approach that targets those.
The Gang Legislation Amendment Bill would ban gang insignia in public places and give police greater powers to stop gang members congregating.
The bill is being considered by Parliament's Justice Select Committee, which this morning heard from submitters who said it would likely not result in a reduction in gang members and crime.
Eugene Ryder arrived at the committee wearing three t-shirts, and challenged MPs present to decipher which had a gang symbol on it - none did, as it turned out, since wearing one at Parliament would be a crime.
He said he was not a gang member - and he had successfully had his name stricken from the list a decade ago - but Black Power was still his whānau.
"I was a state ward, I was abused while I was in care, and I found solace in the Black Power community here in Wellington ... the people that were put in charge on behalf of the state to care for us were raping us. What we learned from that was violence, extreme violence."
Ryder said he had been one of those in the community who had been involved in criminal activity, but the bill being debated held a lot of risk as it would criminalise people because of their associations rather than their behaviour.
Even if it meant every gang member stopped wearing insignia, many would just wear colours and tattoos, he said.
"Would that reduce the intimidation, or the fear of society about them?" he asked. "I think whether you are part of a gang whānau or not, you should be able to share the same rights as every other New Zealander."
He was concerned the law would also mean those associated with gangs would fear accessing the services they needed, and mean the police would target those they believed were more likely to be gang members.
"Someone who's doing criminal activity should be caught and punished - and there's a law for that. But I don't think it's appropriate for someone to be made a criminal because of something that they're wearing regardless of what they're doing.
"If the only tool you've got is a hammer, everything is a nail."
He later told journalists many reports had been written over decades that made clear what drivers of crime and gang membership were, but this law would not address those.
"The solutions are there, they've just got to look for them," he said. "Every son wants to be like their dad, so it's not surprising that children of patched members want to be patched members. And to be honest a lot of the members of these gangs, they don't want their children to be in the same position that they're in, there's no one else opening their arms to our tamariki, our rangatahi, some of our marae even closing their doors to our people. So there's very few options for those that are already living in those situations."
Children's Commissioner Claire Achmad similarly pointed to socio-economic disadvantage as making children vulnerable and pushing them towards the gang life, and said she was concerned more Māori would be disproportionately impacted.
Gang membership and gang-related crime was continuing to grow, he said, but the idea that police would be able to go out and arrest people wearing gang patches was not realistic.
"It's just simply not feasible in the vast majority of situations. That would send a message that police aren't able to do their job ... this would be a piece of legislation that would have to be used differently than that.
"Gang members value their patches very highly, and so it's a disincentive if they know 'If we commit serious crimes or we cause public disorder that police are going to turn up at our house with a search warrant and take our patch'."
It could also mean "post-code policing", creating disparities in towns depending on the ratio of gang members to police officers. He acknowledged the law would disproportionately affect Māori, because Māori had higher rates of gang membership, but argued "generally we get it right".
However, dispersal orders currently did not work very well and were not used often, so having them targeted at gang members would make a difference - depending on how the courts interpreted the law.
"You can't arrest your way out of it, but there has to be multiple ways of dealing with it and one of them is to disincentivise joining gangs in the first place. Two of the key ways to do that: take their patches off them ... the other's take their assets off them.
"But then also, you've got to address why are these people joining gangs in the first place."
"Whanganui is where your evidence is," he said. "There was a 15 percent reduction in gang membership and gang association ... there was less gang-on-gang encounters.
"It was a positive experience for the community, for the police in particular, that gang insignia and the banning of gang patches from public places not only had the effect of making people feel safer but it also had the effect of making gangs easier to manage from a police perspective."
However, when Labour's Tracey McLellan asked if the reduction in gang membership was people leaving the gangs or just leaving Whanganui, Laws - a former National Party MP who later joined NZ First - said: "I would assume they did both ... I'm pretty sure they moved".
That showed how unattractive it was to be a gang member if they could not wear their patches, he said.
It also raises the same concerns posed by Queensland, where gang members simply shifted to other states - and those states did not see the same effect when they tried the same approach.
The Free Speech Union said the proposed law took a dangerous approach to rights generally, with definitions of gangs and gang insignia which were much too broad - opening the law up to being abused. They said claims the law in Australia had been successful were arguable and there was little evidence it prevented harm and intimidation.
He said laws like the Crimes Act already included additional penalties for being a member of a gang or organised criminal group, and pointed to a review by a High Court judge in Australia which found offending by gangs was concentrated in a relatively small portion of members.
Similarly to the Free Speech Union, he said the law was offensive to the bill of rights and fundamental human rights laws, and it would inevitably be challenged in the courts because it was a direct breach of freedom of expression.
NZ Council for Civil Liberties chair Thomas Beagle said it also trampled over freedoms of association and assembly.
"These limitations are being imposed on people not because of what they have done, but because we're afraid of what they might do in future," he said.
"Frankly, it's embarrassing."
People accused of being members, associates or prospects of a gang had no real way to argue they were not, he said, questioning whether other groups might be included in future like protesters, or sports fans.
