Campaigners for legalising marijuana used to be amiable libertarians who asked for nothing more than the right to grow or buy their drug of choice and the freedom to smoke it without risk of prosecution as drinkers of alcohol can do.

Anyone who thinks that is all they will be voting for at a referendum next year is going to be surprised when the Government announces some details of what is proposed, possibly today.

The people who have been leading the campaign to legalise marijuana in recent years are definitely not libertarians. They probably don't even smoke pot or anything else.


They are puritans who regard all pleasurable drugs as a problem demanding tighter regulation and much more health treatment.

The reason they give for wanting to decriminalise marijuana is that they believe the criminal law has failed to stamp it out and merely discouraged users from seeking the treatment they need.

But just quietly, they are also excited by the prospect of designing a regulatory regime that may be applied to all drugs, especially alcohol. A "model drug law" it was called in a report produced by the NZ Drug Foundation for the 2017 election.

It will be interesting to see how much of that report's proposals have been adopted in the regime the Government will put to the referendum. One News has had a tip that a minimum purchasing age of 20 will be set for legalised marijuana.

That, of course, was the age public health professors urged Parliament to set for alcohol when they attempted to reduce its availability in 2010. They have never accepted that defeat and will try again at some stage with a new Parliament.

The Drug Foundation's "model law" for marijuana goes much further than any restrictions the public health professors proposed to the previous Government for alcohol. Licensed outlets would be more strictly limited and be "as uninteresting as possible".

No products or advertising could be visible from the street and the shop also must not sell alcohol or tobacco.

Needless to say, big companies would not be welcomed into the new business. In fact today's drug reformers sometimes go so far as to suggest the supply of marijuana could be a state monopoly. I kid you not.

This model continues to be advanced despite the fact it had a little test six years ago when the previous Government was persuaded to take the "health approach" to the belated regulation of synthetic cannabis which had appeared on the market about 10 years earlier.

The number of outlets became strictly limited, no advertising or signage to suggest what they were, products unseen from the street ...

Pretty soon there were complaints from the generally poor communities where the few outlets were permitted. Large groups of hooded, unsavoury characters were gathering at their shopping centre, slipping in and out of the unlovely ("uninteresting as possible") dark and dingy premises where they got their fix.

That is what happens when you don't allow a market to operate in a normal, open, competitive way letting the supply meet the demand.

But the lesson from that test that really worries me is the way that official approval of a drug made it a public liability. Distraught users and parents went on TV to blame the Government for its adverse effects. Somehow we hadn't heard from them in all the years the substances had been on sale without official consent.

If people want to fry their brains with a chemical of any sort, it's their choice as far as I'm concerned. If pot smokers believe their drug of choice is no worse than alcohol, good luck to them. I don't want the police spending their time and taxpayers' money prosecuting them.

But I don't want too much of our limited public health budget spent on them either. And that is what I think would happen if we vote "yes" at next year's referendum.

Marijuana in my brief experience of it long ago is not much fun until it hits you in the head. It is different from alcohol which gives pleasure in moderation. Pot smokers have to get "high".

So I can readily believe the risks of addiction, mental damage and intellectual decline are high too. But I would sooner spend public health funds on illnesses sufferers had not brought upon themselves.

Right now a bill is going through Parliament that will effectively decriminalise possession of personal doses of all drugs. By the time we come to the referendum we might be seeing what the "health approach" to methamphetamine and other drugs really means.

It means implied approval, causing increased use and public liability for addiction. At that point we might decide the criminal law gives the best, cheapest and healthiest message after all.