Drug dealers across the world are laughing at the law as it simply increases their profits, a former police chief said today.
Tom Lloyd, the former chief constable of Cambridgeshire Police, called for the decriminalisation of all drugs, saying that giving youngsters criminal records simply was not working.
Those who engage in "youthful experimentation" with drugs should be afforded the same discretion as ministers and shadow ministers who admit youthful experimentation in their past, he said.
"It seems hypocritical to saddle a young person with a criminal conviction that could blight their lives," Mr Lloyd said.
Giving evidence to MPs on the Commons Home Affairs Select Committee, Mr Lloyd said: "Drug dealers all over the world are laughing at law enforcement."
They like the status quo "because it elevates the price" of their drugs and boosts their profits, he said.
If 20% of dealers' drugs were intercepted at the UK's borders, "that's not a bad tax rate", he added.
Mr Lloyd said increasing the risk to their business "has not worked", but authorities could reduce drugs gangs' profits by increasing the supply.
"Prohibition creates an illegal dealing market", leading to problems for those in communities living near dealers, he said.
"That's why I want the end of prohibition and the start of control and regulation so we don't have dealers on the street."
It comes after Justice Secretary Kenneth Clarke told the MPs last week that the UK was "plainly losing" the war on drugs - and may even be going backwards.
But he insisted he was personally opposed to decriminalisation and that the Government had "no intention whatever" of relaxing the law.
Today, Trevor Pearce, director general of the Serious and Organised Crime Agency (Soca), said he did not agree that the so-called war had been lost.
"I think it's a constant battle and we have to fight that, if we use that metaphor, but I do not think we have lost."
Estimates suggested Soca seized 30 per cent of the UK's cocaine market, and 10-13 per cent of the heroin market, each year, with 95 per cent of these seizures taking place before the drugs come to the country, Mr Pearce added.
Mr Pearce said he was against decriminalisation, adding that organised crime gangs will look to undermine markets whether they were legitimate or not.
"If we've got a legitimate market, people will still seek to undermine the legitimate market," he said.
"There will always be a two-tier market."
Earlier, Mr Lloyd said: "We do not have control of the drugs market, the criminals do.
"I am seeking to gain control of that so that the dangers inherent in taking the drugs are reduced, the criminality and stigma are reduced, and the treatment opportunities are increased."
He added: "I'm simply seeking to reduce the pain caused by banging one's head against a brick wall, which is our approach to prohibition."