Drug dealers across the world are laughing at the law as it simply increases their profits, a former police chief said on Tuesday.
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," Lloyd said.
Giving evidence to MPs on the Commons Home Affairs Select Committee, 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.
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."
His comments come after Justice Secretary Ken Clarke told MPs last week that the war on drugs was not working.
Clarke delivered his gloomy assessment when asked at the home affairs select committee what his long ministerial experience of dealing with the issue had taught him.