Keith Hellawell, the Chief Constable of West Yorkshire, when asked on BBC TV's Panorama tonight if he sees a possibility of cannabis being legalised in Britain one day, replies: 'I think we all must. The legalisation I do see coming, after an understanding on the effect on our society.'
He adds that current policies on drugs are not working, and calls for a wider debate on cannabis.
Mr Hellawell is believed to be the most senior policeman so far to countenance publicly the legal sale of marijuana, and his comments will be reinforced by a report today from the Institute for Public Policy Research, which recommends that cannabis should be decriminalised for five years as an experiment which could lead to permanent legalisation.
The study by the left-wing think tank, Drugs and Young People, also claims that the Government and parents should try to control the consumption of alcohol and tobacco rather than soft drugs which are not considered a problem by most young people.
The legalisation of cannabis could 'prevent thousands of otherwise law-abiding young adults from being arrested and alienated', the report says.
Its authors, Les Gofton, a lecturer in behavioural science at Newcastle University, and Frank Coffield, a professor of education at Durham University, call for a five-year trial in which the possession of cannabis - as opposed to supplying the drug - for personal use would no longer be a crime.
During the experiment independent researchers would examine the level of cannabis use, the consumption of other drugs, and the effect on police budgets and relationships with young people. If the results are good then the Government could legalise cannabis, initially for a five-year trial, they say.
To combat the increasing availability of narcotics the authors call for drug education to be 'radically restructured and based on a policy of harm reduction'.
'Official drug education, based on the barely disguised text of 'Thou shalt not', is literally incredible to those young people whose own experience flatly contradicts the official line.'Reuse content