An MP from each side of the debate joins Stuff political reporter Jo Moir to debate cannabis reform.

As part of Stuff's 'What if it was legal?' series, we got two politicians from either side of the argument to debate the merits of cannabis reform. Here are four key moments from the debate between Green MP Julie Anne Genter and National's Simon O'Connor.

HOW BAD IS CANNABIS, REALLY?

Genter, who has a medicinal cannabis bill in Parliament, reckoned cannabis was just not very harmful.

"The truth is that regulating and legalising the use of cannabis for adults is the best way to minimise the harm associated with drug use," Genter said.

"And the truth is that cannabis isn't a very harmful substance."

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O'Connor, chair of the health select committee, said we should be trying to curb the supply of drugs in society.

"Drugs often interact with each other so even if it is less harmful, say, than alcohol there's a whole combination effect which we know is far more dangerous so in other words why would we add more drugs into society."

JUST SAY NO

National MP Simon O'Connor and Green Party MP Julie Anne Genter debate cannabis policy

O'Connor said there was a contradiction at the heart of the pro-reform argument.

"It's a contradiction to be saying, 'hey here's a substance we prefer you not to use but it is going to be acceptable now', while also trying to stop people from using substances like tobacco and alcohol, or reducing their usage of it. I think it's instant mixed messages."

But hold on, said Genter, there's a big difference between the harm associated with cannabis and other drugs, like methamphetamine.

"By legalising cannabis and regulating it we can ensure there's more responsible use of it and we can educate people better," she said.

"The truth is that cannabis isn't on the same level as some of those other harmful substances."

CRIMINAL OFFENCE

"The harms associated with drug use and drug abuse are health issues," Genter said.

"They aren't criminal issues. We're never going to resolve them if we make people criminals and lock them up rather than dealing with the fundamental underlying problems."

But O'Connor said we shouldn't budge. Just because alcohol and tobacco had come into the mainstream, that did not mean cannabis should follow.

"Something like cannabis I would argue hasn't been well integrated into society. Yep, a lot of people use it, [but] we're not saying it's acceptable or should be acceptable," he said.

MEDICINAL USE

Genter said the law treated responsible adult use of cannabis as though it was the same as the abuse of a substance.

"Making the whole thing illegal completely denies the fact that there is the possibility for responsible adult use of cannabis and that we can't minimise the harm...if we continue to prohibit. That's not reducing the harms associated with it."

Genter argued for taxable, restricted access to cannabis with the revenue spent on addiction treatment.

O'Connor countered: "So you're levying on a harm."

"You're saying to people, 'we know this is not going to be good for you, but we are going to now actually regulate and take money off you for that', whereas the current system says you shouldn't be involved with these drugs, but we still will fund health interventions to help you. That's a very odd situation you're developing."

Julie Anne Genter is an American-born New Zealand politician with the Green Party. She's the party's health spokesperson and in June her Misuse of Drugs (Medicinal Cannabis and Other Matters) member's bill, which would make it legal for the terminally ill and those suffering a debilitating condition to use cannabis with the support of a doctor, was drawn from the ballot. Julie Anne is in favour of the legalisation of cannabis, which is also Green Party policy.

Simon O'Connor is a National Party MP and chairs the Health select committee at Parliament. O'Connor is against the legalisation of cannabis in New Zealand, a position his party shares. Simon studied for the priesthood with the Society of Mary but when he came to be ordained he decided it wasn't for him and instead pursued a career in politics.