The two reasons for having any public law are that the law reflects public wishes and that it works.

We used to have anti-booze laws that simply didn't work. Men drank like crazy because soon the bar would shut. In districts where 6 o'clock closing was ignored, drinking turned furtive: the police might raid the pub any minute. But not without warning. Everyone knew which pubs flouted the law - and how easy it was to avoid prosecution.

When the local police sergeant inspected a pub around 5pm he regularly placed an overnight bag on the bar, then, upon leaving, he picked it up again without asking why it was heavier than when he placed it there. It was the whisky that was the sergeant's price for playing the game and not jumping on every little breach of the law.

I suspect that, if anything, the anti-marijuana law has a similar result. It offers people the thrill of lawbreaking and tempts kids to have a try.

The last time I chucked off at the marijuana law, a Northland school teacher wrote a derisive letter. How, she asked, would I like having to appear before a room full of kids who had burned their brains out with marijuana? For a day I struggled to write a polite reply and not to ask whether she was such a bore that pupils switched off at the sight of her. And why did she defend the law if she so objected to its outcome?

But politeness would not come and I abandoned the effort. That was a shame because with a bit more thought I might have come up with the most vicious and unjust part of the anti-marijuana law.

It is this. An innocent landowner is treated as a criminal if trespassers plant marijuana on his land.

It happens that a stretch of moist and sheltered land lies at the tip of my north-west frontier paddock. The man who grazes sheep on my vineyard and I both hesitate to go there because we suspect that it has trip-wires attached to shotgun triggers, and even fishhooks suspended on invisible nylon lines. These are the defenses put up by people who invade strangers' land and cultivate marijuana there, simply because the law says they must not grow marijuana among their own silverbeet.

I don't mind people coming here and shooting rabbits, but I don't want them blown away by trip-wired shotguns. And I don't want to be fined if someone sneaks over the fence and sows marijuana seed on my land.

Sure, I can see why the law tries to make me responsible. It's so the police, if they suspect me but have no proof, can still nail me merely by saying that some plants were growing on my land. I say to hell with that. I don't use the stuff, don't grow it and am not a dealer.

The law is unjust and does nothing to stop the spread of drugs. Worst of all, it undermines the principle that we are innocent until proven guilty.

I say the Government is riding for a gutser when the courts laugh at its bids to persecute innocents. Only then shall we get an anti-drug law that cuts down on drug use and gives up trying to punish people who have done no wrong.

© Copyright 1999, NZ Herald