Why MPs won't take a side in the marijuana debate

Two more MPs have declined to say whether they'd be likely to vote in favour of legalising recreational use of marijuana.

On Thursday, AM Show host Duncan Garner put the question to Police Minister Stuart Nash, who said he was still on the fence.

"I'm not going to give you a yes or no, because I want to see what this looks like," he said. "I'll weigh up the benefits and I'll vote accordingly."

Some overseas jurisdictions that have legalised it have reported increased tax revenue, falling crime rates and fewer fatal traffic accidents

According to the Drug Foundation, the drugs that cause the most harm in New Zealand are tobacco and alcohol - both legal. Marijuana is also widely considered less toxic than alcohol, with it virtually impossible to overdose on.

But MPs are still demanding more evidence. 

"You know it does some harm, the question is how do you actually limit that harm the most?" Mt Roskill MP Michael Wood told The AM Show on Friday.

The Labour-NZ First coalition promised support partners the Green Party a referendum on personal marijuana use by 2020.

Mr Wood, a Labour MP, appears to be leaning in favour - but still won't commit.

"I'm increasingly seeing a lot of evidence which tells us that actually if you go down the track of educating people and putting resources into harm minimisation rather than criminalising, you potentially minimise the harm. I'm increasingly feeling like that might be the way to go, but I want to see more of the evidence."

Judith Collins and Michael Wood.
Judith Collins and Michael Wood. Photo credit: The AM Show

National MP Judith Collins said her party supports medicinal cannabis, and that personal use will "probably" end up legalised soon.

"It doesn't take away the harm that cannabis can cause to people, both not only to brains but also to lungs. Five times more tar than cigarettes, by the way."

While it's true marijuana does contain significantly more tar than tobacco, studies have found no link between long-term marijuana use and lung cancer. Scientists say it's probably because most marijuana users only smoke one or two joints a day, while many cigarette smokers will burn up 30 or 40. There's also evidence THC - the psychoactive substance in marijuana - could have a slight preventative effect.

Ms Collins says her view is close to that of Mr Nash.

"I can see that there's not a lot of point, and police certainly have stopped prosecuting people for possession… There are 70 percent fewer prosecutions than there were 20 years ago…

"The problem is once you say something's decriminalised or it's fine and we're going to have it sold in pharmacies and shops, people think it's okay. We say that with so-called synthetic cannabis - it was actually completely able to be sold in various places, and it just took off.

"We're parents, and we don't to send messages to our kids and other people's kids that something's just perfectly fine. Actually, it's not perfectly fine."

Mr Wood says whichever way their vote falls, they'll end up "kicked in the head on this issue".

"I would like us as a country to have a really intelligent debate that looks at the evidence."

Mr Nash, despite his fence-sitting, also appears to be leaning in favour - at least of significant drug reform, if not legalisation - recommending AM Show viewers check out a book on how the war on drugs has failed.