During Prohibition, rotgut was the name given a specially foul whiskey distilled with the rusting radiators of abandoned Model-T Fords. Today's equivalent is a form of lung-rot marijuana which has been poisoned with a herbicide called paraquat.

This substance is being sprayed on the pot fields of Mexico at the behest of and with equipment and technical advice from our government. It is a particularly bitchy thing for the government to be doing when it is also advocating the decriminalization of use of the stuff. In effect, people are being told it is okay to buy grass - that it's legal or shortly will be in most places - but be careful, for what Big Brother gives with one hand he taken away with the other; he has poisoned the pot he's making it legal for you to possess.

None of this, let it be said quickly, is an argument for smoking unpoisoned pot, but millions do it, whatever newspaper writers may say. The reason that paraquat-poisoned pot is causing such a stench is because those who smoke grass are a very loud and very articulate segment of our population.

A letter received here from a marijuana retailer who signs herself The Black Widow helps to explain why the fuss over this question is so loud. She writes:

"Back in the '60s, marijuana was hard to come by and dealers were, by and large, underworld-type characters whom one met on street corners and in parking lots and phone booths. It was all very clandestine and cloak-and-dagger; but then I was in my 20s and the paronoia merely added an adrenalin rush to the spice of life. As I grew up, so did the rest of my pot-smoking generation and we are now the establishment, salaried and respectable - but still potheads. This has created the demand for a new type dealer, one who is part of the middle class culture, who operates discreetly, honestly and dependably. The Business has moved from the streets of the ghettos into the parlors of the middle class."

Well-educated and well-situated people will squawk when their interests are affected adversely, and they know how to do it so the rest hear the noise. This is true of the customers and apparently is also true of the dealers. This, at any rate, is the description Black WIdow gives of persons in the same business:

"The majority of the dealers and suppliers I've known in the past few years are in the Business in order to support another, legitimate endeavor, e.g., artists for whom dealing provides a living so they can paint or script, photographers, move-makers, writers, crafts people; mental health professionals who can then treat the poor . . . We are the highly educated but low-income segment of this society. I am one of this number."

As Black Widow explains how she built her enterprise, and how she runs it, it appears next to impossible for the government ever to catch up with a significant number of such dealers and arrest them. "I have built my business up very slowly (i.e., safely), and now clear about $1,300 a month - not a fortune, but enough to both support me and provide the means for my getting out of the Business in the near future to do what I really want to do," she says in words that, with a few alternations, might be the history of a million American small businesses.

"And now we have to worry about the pot being contaminated with herbicide. That makes me furious. Of course, I'll protect myself and my customers by having all imported marijuana chemically analyzed before I sample or sell it, but that's just an additional hassle and expense." Change a word or two and it sounds like the guy with the small broom factory wailing that the Occupational Safety and Health Agency (OSHA) is putting him into bankruptcy.

The advantage of certain illegal businesses is that because they are illegal the government can't really regulate them and can't adequately collude with one or two large corporations to make a monopoly against the drift of market forces. Black Widow reports that the Mexican spraying operation, although it may kill and maim a few who don't buy from reliable dealers such as herself, will not destroy the Business. The market is adjusting and uncontaminated American production is on the rise.

Indeed she says, "Domestic sinsemilla is the best thing on the market these days in my opinion." According to her menu, as she refers to her price list, American domestic sinsemilla tops go for $100 an ounce or twice what she is currently charging for chemically-tested pure Mexican Red. (Parenthetically, she is selling high-grade, Afghani Primo for $190 an ounce and brownies for two for five bucks.)

It can't be good for you - what drug is? - but the Black Widow has a point. Even at the risk of undermining her own business, she says if they're going to legalize possession, then at least legalize growing it in flowerpots and on windowsills.