POTDavidMcNew:Getty

My London column today is on the dramatically shifting landscape for marijuana in the US, with growing acceptance of medical cannabis, growing numbers of states allowing it, California's consideration of outright legalization and taxation, and the Obama Justice Department's decision to let states govern themselves on the question, without federal interference. It comes after the Labour government has actually tried to increase penalties for pot - against the advice of its own chairman of the Advisory Council on the Misuse of Drugs (ACMD). The wonderfully named Professor David Nutt was fired by the government after he noted certain quite obvious facts:

Professor Nutt had become a thorn in the side of ministers with his criticisms of drugs policy. He clashed with former home secretary Jacqui Smith when he suggested ecstasy, which causes 30 deaths a year, was less dangerous than horse-riding, which causes 100 deaths a year. He also argued that, to prevent one episode of schizophrenia linked to cannabis use, it would be necessary to "stop 5,000 men aged 20 to 25 from ever using" the drug...

The Home Secretary asked him to consider his position after a recent lecture in which attacked what he called the "artificial" separation of alcohol and tobacco from other, illegal, drugs. Last night Professor Nutt said he stood by his comments. "My view is policy should be based on evidence. It's a bit odd to make policy that goes in the face of evidence. The danger is they are misleading us."

"The scientific evidence is there: it's in all the reports we published. Our judgements about the classification of drugs like cannabis and ecstasy have been based on a great deal of very detailed scientific appraisal.

"Gordon Brown makes completely irrational statements about cannabis being 'lethal', which it is not. I'm not prepared to mislead the public about the harmfulness of drugs like cannabis and ecstasy. I think most scientists will see this as an example of the Luddite attitude of governments towards science."

He repeated his view that cannabis was "not that harmful" and that parents should be more worried about alcohol.

They should. Alcohol is far more dangerous to the individual and to society than marijuana. Brits, of all people, should know this. If pubs served pot rather than beer, violent crime in Britain would plummet. Mercifully, the science establishment is fighting back against the firing of someone for telling the scientific truth. Two other scientific advisers have now quit in protest.

(Photo: Various types of marijuana are on display at Private Organic Therapy (P.O.T.), a non-profit co-operative medical marijuana dispensary, on October 19, 2009 in Los Angeles, California. The city of LA has been slow to come to agreement on how to regulate its 800 to 1,000 dispensaries. Californians voted to allow sick people with referrals from doctors to consume cannabis with the passage of state ballot Proposition 215 in 1996 and a total of 14 states now allow the medicinal use of marijuana. By David McNew/Getty Images.)

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