Cannabis is the talk of Britain. There are lots of words for it: marijuana, pot, puff, blow, grass, skunk, purple haze. A quarter of all 15- and 16-year-olds admit to using it. Six million of us have tried it - 1.5 million have a regular spliff. Just one group of people is oblivious to the phenomenon: top politicians hate talking about dope.
The law is being made an ass, but question Michael Howard, the Home Secretary, and he'll tell you that change is out of the question. Jack Straw, his Labour shadow, (and one-time fun-loving student leader) will go red in the face of suggestions that the main parties should come up with a better "joint" policy.
You can see why they're cautious. A substantial minority may be drawing on their black Leb, but most voters still hate the whiff of weed. Six out of 10 believe, according to a poll commissioned by the Independent, that the drug should remain illegal. Even among the 15-24 age group almost half oppose bringing cannabis within the law. Of course, this means that lots want change, but party policies are studiously ignoring them. "Give the majority what they want, don't let the minority smoke what they want," is the motto.
And when Clare Short abandoned orthodoxy and called for a rethink on pot, her initiative was firmly stubbed out. Stay on line was the word from Labour's smoke-filled backrooms, forcing yesterday's apology from the Labour front-bencher.
Yet Ms Short knows, as well as her colleagues, that this popular phenomenon will not be blown away by silence. Cannabis is cheap and readily available across the country: pounds 7.50 - the price of a round of drinks - will buy one-sixteenth of an ounce, enough to keep a group of youngsters mellow for an hour or two. And it is considered relatively harmless. Against the hundreds of thousands of deaths associated with tobacco use and health problems produced by alcohol, a spliff seems innocuous to many people.
The police appear to agree. Senior police officers want reform. On their patches, they are changing policy on the quiet. Offenders are treated more leniently than in the past: those receiving cautions for cannabis possession have risen from 1 per cent of cases in 1981 to 45 per cent in 1992. But policy varies greatly around the country: Sally Murray of the Kaleidoscope, a drug rehabilitation centre, says: "It depends on the whim, knowledge and intelligence of individual officers."
But official policy remains unforgiving. The law retains draconian provisions. The maximum penalty for possessing cannabis is still five years in jail plus a fine: dealing in the drug could leave an offender behind bars for 14 years. The jailing of Graeme Steel, son of Sir David Steel, the former Liberal Democrat leader, shows what can happen: he was sent down for nine months after police found 40 cannabis plants at his home. Cannabis use is also landing more and more people with a criminal record. In 1993, more than 50,000 people were so branded for using cannabis, almost three times as many as in 1983.
So is it now time to liberalise the law? Opponents of change marshal a number of arguments. First, they put forward the "escalation theory", the view that cannabis use leads directly to the purchase of harder drugs such as heroin. They point out that cannabis is the first illegal drug that most present heroin users bought. But this does not clinch the argument since the majority of cannabis users never try anything harder. Indeed, it is frequently contended that making cannabis legal might actually reduce heroin use by cutting down on the number of people consuming unlawful narcotics and so making themselves open to trying other illegal substances.
Health is the next issue that conservatives raise. We do not know the long-term effects of cannabis use, which may cause cancer of the lung and other parts of the digestive tract. The drug contains high concentrations of potentially carcinogenic tar and users tend to inhale more deeply than cigarette smokers. There is a raging medical controversy on this issue. In 1992, Gabriel Nahas, Professor of Anaesthesiology at New York University, alleged that marijuana carried a serious cancer threat. But his evidence, methods and quotation of literature have been heavily attacked by his peers as unreliable.
There is another health problem, namely the strength of cannabis now available. Potency has increased hugely following the cross-breeding of plants and genetic engineering, which means that a spliff may now not only give a sense of relaxed well-being, but hallucinations that could damage anyone who was mentally unstable.
Despite these concerns, it is hard to sustain the cannabis ban on health grounds as long as tobacco remains not only legal, but also widely advertised. There is little evidence that the danger to adults of consuming cannabis is so great as to justify the state curbing civil rights.
The real reason why the leadership of the two main political parties have decided not to reform the cannabis laws is because each is worried about being labelled soft on drugs by their opponents. The pillorying of the Liberal Democrat conference in 1994, after delegates voted for a re-examination of the issue, gave a clear warning to any serious politician tempted to break ranks.
Against these cautious conservatives running the main parties are ranged the back-bench reformers. Right-wing libertarians such as Teresa Gorman see the state as having no right to interfere. They have found common cause with Labour leftwingers such as Tony Banks angered that so many are needlessly being outlawed.
There is, however, a great range of opinion among reformers about the extent of change that is needed. The easiest measure would be to repeal the 22-year-old ban on the medical use of cannabis for conditions such as multiple sclerosis: two-thirds of people would support this amendment, according to our opinion poll.
Others argue for general decriminalisation of cannabis. Users would be subject to a token fine if caught in public, but face no greater penance than those guilty of a parking offence. But most campaigning groups, such as Release, the national drugs and legal advice service, want more dramatic change. "If we had proper legalisation," says director Mike Goodman, "we would have proper quality control of this drug, taking it out of the criminal world and making sure consumers and young people had the same protection that applies to other products."
The rational argument looks to be in Mr Goodman's favour. It may be time for politicians to relax, loosen up a bit. But this week's censoring of Clare Short suggests that they remain a long way from being capable of conducting a serious debate about the issue, let alone instituting liberal reform.