One of the great achievements of humankind is the European Enlightenment. Governments base their policies on empirical evidence, there is a prime place for science to inform how we think and act, and superstition and blind prejudice are cast out of the public domain. But the UK’s most prominent drugs expert, Professor David Nutt, could be forgiven for thinking today that the Enlightenment tradition is dead and buried in his country.

Professor Nutt was sacked as chair of the Advisory Council on the Misuse of Drugs last Friday by UK Home Secretary Alan Johnson. His sin — disagreeing with a government view that cannabis is so harmful that it should classified as a lethal drug. Nutt’s view is that smoking dope is less harmful than cigarettes or alcohol and that it creates only a relatively “small risk” of psychotic illness.

Nutt had the support of the other members of the Council — they collectively think that Prime Minister Gordon Brown and his government are bonkers for running around saying that cannabis kills. In April last year Brown proffered the extraordinary view that “so much of the cannabis on the streets is now of a lethal quality”.

Brown and his ministers conveniently ignore what Nutt is actually saying about cannabis and other drugs. In a speech delivered last week at King’s College London, Nutt set out, with all the care of the scientist that he is reporting, findings of years of research in to the issue of drugs and the harm they do.

“No one is suggesting that drugs are not harmful. The critical question is one of scale and degree.

“We need a full and open discussion of the evidence and a mature debate about what the drug laws are for — and whether they doing their job?” Nutt argued.

That a scientist should be sacked by a government for simply asking that policy in an area be based on science and fact rather than prejudice and politics is more than disturbing, it smacks of authoritarianism.

Home secretary Johnson admits as much today when he told the media that Nutt was being sacked because he disagreed with government views. In a letter to The Guardian, published this morning, Johnson says, “Professor Nutt was not sacked for his views, which I respect but disagree with. He was asked to go because he cannot be both a government adviser and a campaigner against government policy.”

The sacking of Professor Nutt and the Brown government’s bald admission that it does not want scientists on advisory committees who disagree with government policy has serious implications for policy making in areas such as climate change, GM crops, nuclear power and a whole range of areas where it is fundamentally important for security and economic reasons that vested interests and political agendas of any colour be relegated to good science based outcomes.

Don’t think that what happened to Professor Nutt is unique to the UK. CSIRO sacked Dr Maarten Stapper in 2007 for his critique of GM crops. And earlier this year four senior CSIRO scientists who criticised the Rudd government’s climate change policy were gagged by their bosses.