The UN officials who condemned Britain's celebrity culture for glamorising cocaine yesterday presumably haven't watched the footage of Amy Winehouse in sandals, with injection marks between her toes. If these teetotal bureaucrats think that the singer's fans will follow her on to crack, they are far more naive than the British public. For people under 40, drugs are ubiquitous. Most of my generation thinks of cocaine much as our parents thought of single malt. Kate Moss, if the rumours were true, was just joining in with the mainstream. Whereas Amy has clearly gone beyond - as the thousands of bets on whenwillamy- winehousedie.com seem to testify.

The most powerful role models are dealers, not celebrities. All over Britain, men in gold jewellery flaunt their wealth at school gates. Teachers tell me how hard it is to convince teenagers to get NVQs, when they can have a career with Drugs Inc and aspire to make £1,000 a day. Drugs Inc is one of the most profitable, successful businesses of all time. The UN values it at about $330 billion, almost as big as the defence industry. The criminals who run Drugs Inc shift staggering amounts of stock with no conventional advertising. They offer free samples to children and discounts for trading up to harder substances. They motivate their salesforce with threats.

As a result, drugs are now the second-largest revenue earner for organised crime. The profit margins, according to the Downing Street Strategy Unit, are higher than those on luxury goods. Drugs Inc pays no tax. And with so much money at stake, its barons are vicious. Violence has soared as rival gangs battle for a share of the profits.

Two weeks ago Sunday Essiet became the fifth teenager to be murdered in London this year (and we're only two months in). The little Nigerian boy was “kicked like a football” in Plumstead, the victim of what residents claimed was a drug turf war between white and Somali groups. A few months earlier a 13-year-old girl had been knifed in her playground in mid-afternoon by rivals of her friend, an 18-year-old drug dealer. These are children. What better demonstration is there that the “war on drugs” has failed?

We won't end this violence by jailing celebrities or middle-class users. The only way to take back our streets is to wrest back control of the drugs from the criminals, by legalising and regulating their trade.

Imagine if you could buy coke from Boots. Or the aptly named Superdrug. That would drain the glamour from it more effectively than making a martyr of Kate Moss. I don't imagine her lovely features would adorn state-regulated packets of white powder, hanging next to the corn plasters. Yes, legalisation would make drugs cheaper, in order to undercut the dealers. Yes, usage might increase. But perhaps not much, because it is already widespread. A third of 16 to 24-year-olds routinely admit to having tried drugs, despite knowing that they are admitting to a crime.

The benefits of legalisation could be enormous. Overcrowded prisons would be relieved of people needing treatment rather than punishment (about 15 per cent of prisoners are in for possession or supply). Addicts would not be forced into associating with criminals. Children could be safe in Britain's playgrounds again.

Something similar happened in 1933, when America repealed Prohibition. The ban on alcohol had corrupted the police, increased the number of hard drinkers and created a whole new criminal class of bootleg suppliers. Britain's equivalent of Prohibition was the Misuse of Drugs Act of 1971. Up to that time we had treated addiction as an illness, heroin addicts got their fix on prescription, and there were only 5,000 problematic drug users, according to Transform, the drug policy group. Thirty years on there are 280,000. That is a direct result of Drugs Inc, which makes more money from pushing harder substances. Our laws have created crack, a concentrated form of cocaine, and skunk, a concentrated form of cannabis, both of which are devastating.

The prohibitionists fail to distinguish between recreational and problem users. The vast majority of people stick to recreational use of cocaine, Ecstasy and substances that even the Strategy Unit has classified as low-risk. There are tragic cases, of course, but they are often caused by impure supplies. Cocaine and Ecstasy can be cut with other substances. Glass has recently been found in cannabis - another nasty aspect of Drugs Inc that would disappear if the market went to Boots.

Annual deaths from drug use (about 2,000) are still minuscule compared with those related to alcohol and tobacco (about 160,000). These figures are not precise, because some people abuse all three. But it is arguable that the violence associated with the illegal drugs trade does more harm than the drugs themselves.

The irony is that it is the UN and its drug conventions that are the biggest barrier to progress. Its ideological war on drugs makes it almost impossible for countries to be pragmatic. It has demanded that Portugal, which decriminalised possession, should recant. Yet Portugal has accepted the reality that in GDP terms, it is dwarfed by Drugs Inc. As a result, it has seen crime fall.

The only way to make our streets safe is to wipe Drugs Inc off the map. The only way to do that is to legalise the trade. That would also redraw the map, because drug lords from Colombia to Afghanistan would no longer find the trade so lucrative. The UN's blindness to this is unforgivable: even worse than its failure to understand that Amy Winehouse, despite her beautiful voice, is the perfect health warning.

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