The cover of the latest report from the Commons home affairs select committee asks: "The government's drugs policy: is it working?" But no committee is required to answer that question. The government's drugs policy is not working, and nor is any other government's. Governments have declared a war on drugs. Politicians love to declare wars: on terrorism, crime, litter, teenage pregnancy, street begging, hooliganism - just about anything generally agreed to be bad. Wars allow politicians to inflate their importance and to strike dramatic, decisive poses; dissenters may be dismissed from public debate as traitors who undermine the war effort or even as enemy agents. But these wars are rarely won. The war on drugs has been a Waterloo for almost every government on the planet. The victims, as always, are not the politicians themselves but the poor.
The select committee proposes prescriptions of heroin for addicts and an experiment with "safe rooms" for injections - a sensible and urgent reform. The rest is tinkering. The MPs want cannabis reclassified - but only so that the constabulary cannot burst into your home to inspect your plant pots and so that you may be imprisoned for a mere two years, instead of five. The maximum penalty for possessing Ecstasy, under the committee's proposals, would be down from seven to five years, and supplying it would no longer carry a risk of life imprisonment. Even that is too much for David Blunkett, who has simply declared a new war. It occurs neither to him nor to the select committee that any debate should start from John Stuart Mill: "Over himself, over his own mind and body, the individual is sovereign."
In other words, when it comes to individual behaviour, the onus of proof should always be on those who wish to legislate. Nobody denies that drugs, legal and illegal, can ruin lives; tobacco alone is implicated in more than 100,000 deaths a year. It was alcohol, in the form of gin, that was thought most ruinous in Victorian times (though opium, in the form of laudanum, was also widely available). This was what led to the fierce temperance campaigns of the early 20th century, and ultimately to the strict English licensing laws and to prohibition in America.
But prohibition proved to be one of the greatest public policy failures in history. The alcohol trade continued to flourish, but in the hands of criminal gangs. It became an unregulated free market and, as in all such markets, the consumer was mercilessly ripped off: alcohol was frequently adulterated with methylated spirits (which explains the prevalence of blind blues singers in that era). Exactly the same happened with heroin, which was not actually banned in the US until 1924, four years after alcohol. In its pure form (and, even more so, in its unconcentrated form as opium, smoked through a pipe), it is, to quote a Department of Health official who gave evidence to the select committee, "not particularly dangerous". Mixed with drain cleaner, sand or cement dust - common tricks among street entrepreneurs - and injected into the veins with an unsterilised needle, it becomes, unsurprisingly, lethal.
Worse, heroin, sold illegally, becomes a threat to the rest of us. Because the black market charges a premium price to cover the risks of illegal trading, and because heroin is highly and progressively addictive, users need to spend ever higher proportions of their income on the drug. They therefore turn to crime to finance their habit. They also themselves become suppliers, seeking out new users. As the journalist Nick Davies told the select committee, this is the most effective form of pyramid selling ever invented: since the laws on prescribing heroin were tightened in 1971, the number of users has grown from a maximum of 1,000 to anything between 200,000 and 500,000.
There is room for genuine doubt and disagreement over the dangers of various drugs; even cannabis (fashionably regarded as less harmful than either tobacco or alcohol) may turn out to be associated with lung cancer and mental illness, and possibly also with a loss of drive and ambition. The argument for legalisation of drugs is not about their safety but about the best ways of controlling their dangers. The wars against them have failed utterly. Drugs are more widely available and more widely used than ever. The various classifications should determine not a hierarchy of criminal penalties but different forms of supply: prescription only, say, or wide availability on specifically licensed premises. The argument should be about degrees of regulation, not about degrees of criminality. The penalties should be reserved for antisocial behaviour - driving cars or beating people up under the influence of drugs - not for the use of the drugs themselves. The restrictions should be on sales to children, not to consenting adults. The deterrents that we emphasise should be health risks, not spells in our already overcrowded prisons. We follow all these principles for tobacco and alcohol. Perhaps legalisation would lead to more young people taking up more drugs (probably the same young people who now smoke and drink to excess). Or perhaps not. Any fool knows that, to many, drugs are more attractive precisely because they are forbidden.
The select committee concludes, rather pathetically, that "however forceful the arguments . . . no other country has yet been persuaded to legalise and regulate". And to move effectively to a new regime, Britain would need international agreement. But if Mr Blunkett cannot be persuaded of its merits, perhaps Gordon Brown can. The drugs market is worth an estimated £6.6bn, all of it at present going into the pockets of criminals. The Chancellor can work out for himself what the duty from a legalised supply would yield, and how many of his public spending problems it could solve.