Peter Dunne, the bespectacled politician in the bow-tie, was the unlikely hero of drug reform.

In May, the Associate Health Minister ventured that "some, if not all" class C drugs should be reclassified and regulated.

Outraged cries of "Minister for Stoners" were conspicuous by their absence.

That Dunne, a 63-year-old, 11-term MP should be the one to fly the kite for drug reform - and hit no particular turbulence - said a lot. Perhaps he was not such an unlikely hero after all.

Three-quarters of adult New Zealanders have tried cannabis. Diversion for low-level personal cannabis use is common. And the Government has recently made allowances for some medicinal cannabis use.

So, what if it was legal?

Today, Stuff launches a major series exploring that prospect. What would happen if farmers could sow cannabis crops? Would gangs suffer from it becoming legal? Could our health system manage a possible surge in patients with addiction problems? Is there a massive tax windfall awaiting us in a regulated market?

It's time we explored these questions in detail as, in all probability, a regulated market draws nearer.

There are signs cannabis prohibition could be headed the same way as the ban on same-sex marriage. Only a year or two before a conservative MP stood in New Zealand's Parliament to celebrate "the big gay rainbow" that welcomed same sex marriage, that law change appeared unlikely, at best. We could be in the middle of the same kind of sea-change right now.

A poll last year suggested almost two-thirds of New Zealanders believed possession of a small amount of cannabis for personal use should be either legal (33 per cent) or decriminalised (31 per cent). The split between those for legalisation and those for decriminalisation reflects where the debate really resides: not whether we should change cannabis laws - but how.

Expert opinion weighs even more heavily in favour of change. The status quo seems to be on borrowed time. So we are giving particular attention in this series to what change might look like. There are many different possibilities.

We start today by explaining the basic differences between depenalisation, decriminalisation and legalisation.

We've commissioned independent research from the New Zealand Institute of Economic Research to put a figure on how much might be raised from an excise tax.

On Tuesday we'll host a one-on-one political debate, via Facebook Live. The following day, we'll livestream the Drug Foundation's drug law symposium at Parliament.

We'll look closely at some of the key concerns about loosening cannabis laws. Would addiction rates increase? Would productivity suffer, or workplace accidents rise?

To be clear: this project does not mean we're supporting cannabis use or even advocating for law reform. It means we're advocating addressing the cannabis question head-on, through a candid conversation about the benefits and drawbacks of a change in drug policy.

The debate is at a tipping point and in need of informed discussion in the mainstream. And that includes everyone - the dread-locked, the sports jocks and the bow-tied.