Heroin makes you rob chemists at gunpoint. Cocaine gives you three nostrils and an overdraft. Alcohol makes you violent and stupid. Dope only makes you want sex and chocolate. So why isn't it legal?
it has been a quiet, temperate sort of dinner party - easy on the dry white, heavy on the mineral water. And don't expect to see any brandy, because only plumbers and naff execs with portable telephones tend to do alcohol these days. In the trendiest thirtysomething households, the low-fat pudding will be followed by a lump of something resembling an Oxo cube in clingfilm.

The host courteously lays his stash on the table and soon everyone is licking Rizlas and making admiring noises through blissful lungfuls of smoke. "A nice little Moroccan," he says modestly, "just enough henna in it to flavour."

Not so long ago, dope-smoking was the province of pitiful old leftovers from the Sixties, sitting round on floor cushions and humming along with Tubular Bells. Nowadays, it is making a major comeback in polite society. The etiquette has changed, naturally - a joint each, instead of a wet roach passing from mouth to mouth - but it's the same, fragrant stuff, an ideal and benign digestif after a hard day fighting the recession. If you don't do dope yourself, and don't know anyone who does, I can only ask if you are visiting this planet for business or pleasure? It is as widespread as farting and as publicly unmentionable.

The ridiculous fact remains that cannabis and its byproducts are illegal. Any one of those nice Guardian readers round the dinner table could easily find themselves bending over in a dingy nick, having their bottom searched by some ghastly Plod. The official line, still held by the law and most of the media, is that "pot" is a wickedly dangerous drug, smoked in Hogarthian dens by crazed desperadoes. Smugglers and dealers at the highest levels tend to be nasty pieces of work, but that is a direct result of the law - commodities that are both desirable and illegal attract gangsters. Down in the street, the "drugs baron" dealing exclusively in dope will be merely minor aristocracy.

Where the weed is concerned, even nice, normal, conventional people are starting to agree that the law is a total ass. Look at the Liberal Democrats, led by the pukka Paddy Ashdown, voting for legalisation at their annual conference. Look at Labour's splendid Clare Short, hinting on television that cannabis should be decriminalised. The fragrant and well-born journalist, Mary-Anne Sieghart, when she came out on Question Time with the mild observation that pot was less harmful than alcohol, was only voicing a sentiment you could hear in hundreds of Habitat dining rooms. Yet sections of the studio audience carried on as if she had advocated child abuse. What is all the fuss about? Heroin makes you rob chemists at gunpoint, before killing you. Cocaine (besides being vulgar) gives you three nostrils and an overdraft. Alcohol makes you violent and stupid. Dope only makes you want sex and chocolate. It deadens pain and produces a feeling of happy relaxation. Occasionally it makes you titter inanely at nothing. At worst it can turn you into a monumental, Olympic-standard bore who insists on describing every second of Blue Peter with interjections of "Wow!" and "It was amazing!"

Modern weed-heads do not regard themselves as drug users. They are refined, post-prandial puffers and madly resent the indignity of illegality. To them, a spliff is like a glass of wine, to be enjoyed in mellow company and politely offered round. Unfortunately, Sainsbury's does not stock dope-and-Rizla kits alongside its jars of Stilton. So where, and how, does a genteel person score?

"It's like belonging to a club," explains Matthew, a thirtysomething corporate lawyer. "You know someone who does it, and they introduce you to their dealer. I was introduced to Clarence by a colleague."

Clarence (of course it's not his real name: what do you take me for?) is an amiable Rasta, who runs his little business from the back of a second- hand furniture shop somewhere south of the river. His customers run right across the social scale. "It was dreadfully embarrassing at first," admits Matthew, "going into this shop full of frayed office chairs and reeking of ganja, and hearing my own silly, posh voice asking for an eighth of Jamaican for the weekend."

Heavy customers tend to converse in arcane jargon, incredibly useful if you are ordering over the phone. Just in case the Peelers are onto your dealer's line, you should place your order in euphemisms, such as: "I hear your Uncle Henry has sent some more of his nice home-made jam." A "Henry" means "Henry the Eighth", or an eighth of an ounce, retailing at pounds 40-pounds 50. A "Louis" is a Louis Seize, a poor person's sixteenth. Toffs and old hippies buy in quarters, whopping great lumps that change hands for pounds 100 or so, depending on the quality.

Clarence, patriotic to the ends of his dreadlocks, will smoke and sell only best Jamaican. During the Christmas rush, he has even been known to deliver it to the door. "It was very kind of him," Matthew says warily, "but I wasn't really very happy about having him on the doorstep. It looked so obvious - I don't want to be a snob, but how many of my friends and family have two fathoms of dreads stuffed inside a drooping yellow, red and green tea-cosy? I mean, I am a lawyer. Clarence isn't the sort I'd normally meet."

Possibly, but some dealers these days are almost part of their clients' families. If they are out of a different social drawer, they can be the subject of amusing dinner party anecdotes, along with the cleaning lady, as in: "No, we didn't much care for that film, but our dealer adored it." These days, it is increasingly common to score for your dinner party then invite your dealer to join you.

Ned, who co-owns a London art gallery, is great friends with Christian, who regularly supplies him with Moroccan. "We went to the same public school. He was a terrific pothead even then, so he sells to his chums out of love as much as anything else. I don't know where he gets the stuff, and I don't ask, but when I go round to his house for my ration, I usually offer some to him for a smoke. There might be several other customers there, and we'll have tea and biscuits, and chat pleasantly about this and that. The thing about dope is that it is so sociable."

Goodness, yes. This is the whole point. Only a misanthrope would make a habit of smoking alone. A touch of ganja acts on the most awkward social mix like gelatin. "It doesn't matter how little you have in common," explains Ned, "because the dope is a uniting factor on its own." So much so, in fact, that if you decline, you are in for a very dull time. Slowly, you will watch everyone else melting down into giggling, repetitive idiots, who will then drive home incredibly slowly, while their passenger implores them not to go so fast.

David, a well-known writer, claims that a smoke "intensifies my creativity. I get most of my ideas while walking in the country with a joint." David is a real connoisseur, who also grows his own "skunk" (the king of smokes, crossbred over generations, strong enough to lift a safe) in his wine cellar, though he objects to the term. "It's very nice, actually. Good home-grown is the most politically correct thing to smoke, because it won't have been through the hands or bottoms of anyone dodgy."

Modern legends about home-grown abound - many smokers swear they have seen handsome groves of marijuana growing on Hampstead Heath. Terry, who supplies selected friends with his crop grown under halogen lamps in his loft, claims he uses Richmond Park to "heel in" his seedlings. "I get on my moped and fetch them every so often. Grass in general, and home- grown in particular, used to be thought rather naff compared with blocks of hash. But there is a growing interest in home-grown, because you know exactly where it's been. I'd say that modern users are more health-conscious than the traditional pot-heads of the Sixties. I'm meeting more people who want to put it in food or tea, because they don't like mixing it with tobacco. The nicotine is easily the most dangerous part of a joint."

Clearly, there is a huge gap in the perception of dope, between those who use it and those who think in terms of "drugs" and "drug addicts". The Sixties had a lot to answer for, because it linked smoking pot with political subversion. In fact, marijuana, or cannabis sativa, a member of the hemp family, has been enjoyed all over the world since ancient times.

"God knows what this government spends trying to stamp out dope-smoking," says Matthew. "And God knows how many criminals have got rich, peddling something that should be widely available. Possibly, they are afraid that legalising it would be the thin end of the wedge for other drugs, but until someone gives me proof that occasional use is harmful, I'll go right on smoking it."

Let's get real. Modern pot-heads are too health-conscious to touch any other naughty substance stronger than cholesterol, and wouldn't dream of overthrowing the state. They're too relaxed, for one thing. Give a football crowd dope instead of lager, and when the other side scored a goal, you'd hear nothing worse than a hum of gentle laughter.