A new report from a group opposed to cannabis legalisation shouldn't be dismissed out of hand, a health researcher says.
But its conclusions are based on data pulled from countries with very different legal cannabis regimes than what New Zealand is proposing, according to Chris Wilkins, an associate professor at Massey University.
The report, Lessons from Cannabis Legalisation 2020, looks at what's happened in the US, Uruguay and Canada, three countries who've led the way. It was released this week by Smart Approaches to Marijuana NZ (SAM), which includes the likes of Family First's Bob McCoskrie.
SAM is opposed to legalising recreational use of the drug, which studies show most Kiwis will try at least once in their lifetimes.
"This report, which has almost 250 references, will serve as an eye-opener for the New Zealand public and gives very persuasive evidence for voting no in the referendum," said SAM spokesperson Aaron Ironside.
"The legalisation of marijuana has had significant costs both fiscally and in terms of social and health harms. It is clearly evident that cannabis legalisation is a failed policy."
SAM claims in countries which have legalised cannabis there have been increases in youth use and car crashes, tax revenue has failed to cover increased health costs, and black markets have continued to thrive.
"This report moves past the spin from cannabis industry proponents who want to normalise and profit from drug use in our communities," said Ironside.
Dr Wilkins has studied drug use and policy for 20 years, and in 2019 was appointed to the Prime Minister's advisory group on cannabis reform. He told The AM Show on Monday the report was "credible" but did contain "a little bit of scaremongering as well".
"It's based on a lot of statistics and research. It's obviously got a clear agenda - they're against legalisation of cannabis. But I think it's quite a good report in the sense it gives us some realism. The people pro-legalisation, they're often very optimistic about what this change is going to do."
The facts are, according to Dr Wilkins that legalising cannabis will generate hundreds of millions of dollars in tax revenue, and reduce the number of arrests, potentially freeing up police resources and preventing users from having the albatross of a criminal record around their necks.
It will also diminish the black market - but as SAM suggests, won't eliminate it.
The difference is that New Zealand's proposed regime is much tighter than that in the US, where much of SAM's evidence of harm comes from.
"You can do cannabis legalisation really badly if you don't have strict regulation and you're not really careful about implementation," said Dr Wilkins.
"That really high-potency weed came in the US because one, they didn't have potency caps - which we are going to have here - and also they weren't too worried about what types of product was being sold, and I think that's a real mistake."
The black market here will "adapt" to competing with the legal regime, Dr Wilkins said, perhaps offering the higher-potency cannabis the stores aren't allowed to sell. Overseas experience had found the black market was about 50 percent smaller after legalisation, he said.
"At best you're going to reduce the black market, and everyone involved in the black market is going to adapt. Legalising cannabis is not going to get rid of gangs and organised crime. They will adapt their business model to what opportunities are there."
SAM claims legalisation results in increased use in both youth and adults. Dr Wilkins said it's likely many adults would simply be switching from alcohol to cannabis, which is "in the same ballpark as alcohol in terms of harm", so is arguably an acceptable trade-off. He said research into the public health benefits of legalisation - one of the primary arguments of the pro-legalisation campaign - was still inconclusive.
As for youth, they're already using cannabis Dr Wilkins said - and legalisation, with strict age limits and a diminished black market, would open up opportunities for reducing it. Asked if teenagers would just get older friends and siblings to buy it for them, he pointed out that already happens with alcohol.
"Obviously the aim is to reduce the harm of cannabis and try and increase responsibility and focus on reducing youth use, but the results of that have been pretty mixed to date."
Dr Wilkins wouldn't say if he would vote for or against legalisation in the upcoming referendum.
Even if Kiwis vote in favour of legalisation, the Bill which would set up a recreational cannabis industry would still need to be passed by Parliament.