A professor and long-time drugs campaigner has called for cannabis use to be legalised under licence, despite the disastrous consequences of weakening the law in 2004.
Prof Roger Pertwee claimed that increasing the availability of the drug would prevent drug-related crime and reduce the chance of people progressing to harder drugs.
But weakening the cannabis law in 2004, by downgrading it from a class B drug to the supposedly less harmful category of class C, led to a surge in addictions and mental illness.
In the three years after the law was weakened the number of cannabis addicts receiving NHS treatment doubled.
The reclassification was also accompanied by a surge in the number of children aged 15 and under being treated for mental illness.
And a study lasting 27 years involving 50,000 people showed that smoking cannabis trebles the risk of a young person developing schizophrenia.
The drug was restored to the stronger class B classification in 2008 in response to pressure from judges, police, parents and mental health experts.
But Prof Pertwee’s contentious licensing proposal would mean that anyone who wasn’t suffering from a serious mental illness or at risk of psychosis would be allowed to purchase the drug.
He said: “You’d need to have a minimum age of 21, and I would suggest you might even have to have a license”.
“You have a car licence and a dog licence; why not a cannabis licence?”
But Mary Brett, from the campaign group Europe Against Drugs, cautioned that it was impossible to predict who would react badly to the drug.
She said: “We have been terrible at keeping alcohol away from kids. Why would we want to add to our misery?”
And a spokesperson for the Home Office said: “There is clear evidence that cannabis is a harmful drug which can cause damage to mental health in the immediate and longer-term.
“Even the occasional use of cannabis can be dangerous for people with diseases of the circulatory system.
“The Government does not believe that decriminalisation of cannabis is the right approach. Our priorities are clear: we want to reduce drug use, crack down on drug-related crime and disorder and help addicts come off drugs for good.”
Earlier this year the Government’s new drugs adviser who had previously called for cannabis to be legalised distanced himself from his previous position saying “it’s certainly not my position now.”
During an interview with Radio Five Live Professor Les Iversen said: “We have now to confront the more potent forms of cannabis.
“We have the new evidence that arose since 2003 linking cannabis to psychiatric illness. I think it’s quite free for a scientist to change his mind when faced with new facts.”