Dominic Lawson: Labour's thirst for power led to this confusion over drugs

How many MPs would have criminal records if police had found them smoking drugs?

Alan Johnson has taken a sledgehammer to crack a Nutt. The Home Secretary could easily have ignored remarks by the UK's chief drugs adviser questioning the reclassification of cannabis as a "class B" drug. Instead, he sacked Professor David Nutt, thus guaranteeing a monumental public row. Perhaps that is exactly what Mr Johnson wanted. It creates the impression that the Government is "tough on drugs", one of the three headlines that New Labour has craved above all (the others are "Labour gets tough on crime" and "Labour gets tough on terror").

For it is quite hard otherwise to see exactly why Professor Nutt has been fired. It would not be the first time one of the Government's scientific advisers has publicly indicated that ministers have not taken their advice. When this Government in its 2003 White Paper on Energy decided at the last minute to remove nuclear power from the plans for new non-fossil fuel electricity generation, directly against the advice of its then chief scientific adviser Professor David King, Sir David made it publicly very clear that his advice had been ignored. He remained in his post.

It is said that Professor Nutt had been much less diplomatic than Professor King in his criticism. We are told by Government spokesmen that his lecture to the Centre for Crime and Justice Studies at King's College London, published last month (though actually given back in July) was too "political" in tone. I have read the lecture, and it contains not a single explicit criticism of the Government.

Nutt quotes the previous Home Secretary (Jacqui Smith) saying that the Government's decision to reclassify cannabis "takes into account issues such as public perception" – so I suppose he is letting us know that the Home Office admits it is acting on criteria other than scientific advice; but then he softens the blow by concurring that "the issue of public perception is very important". Nutt does, however, give the following conversation that he says he has had many times "with politicians" when he has told them that the risks from cannabis are less than those from commercially available cigarettes and alcohol:

Member of Parliament: "You can't compare harms from a legal activity with an illegal one." Professor Nutt: "Why not?" MP: "Because one's illegal." Nutt: "Why is it illegal?"

MP: "Because it's harmful."

Nutt: "Don't we need to compare harms to determine if it should be illegal?"

MP: "You can't compare harms from a legal activity with an illegal one." Repeats...

This was presumably the point Nutt was trying to make in a piece published in a scientific journal at the beginning of the year. It was called "Equasy", and it pointed out that horse-riding, or "equine addiction syndrome", accounted for 100 deaths a year, as against 30 a year from ecstasy use. Yesterday, Alan Johnson said: "As for his comments about horse-riding being more dangerous than ecstasy, it is of course a political point rather than a scientific point." There's no "of course" about it. Nutt was simply comparing statistical risks between two allegedly pleasurable activities, and in a peer-reviewed scientific journal, at that; but the thing about the vast majority of politicians is that for them everything is political and they find it impossible to imagine that some of us are not similarly motivated.

It is of course the right of politicians to be political, just as doctors need to be medical; but the New Labour cast of mind is more political than anything we have seen before at Westminster. Perhaps that is because it stripped the Labour Party of its previous ideology-socialism-and therefore could provide no guiding principle for action other than the pure, undiluted, desire for popular acclaim: the key to power in a democracy. As Professor Nutt acknowledged in his King's College lecture: "We carried out our own MORI survey of a representative general population and asked what class should cannabis be?... What we found was that just over half wanted it to be in a higher class [than C]. This surprised us, as did the fact that that 32 per cent wanted cannabis classified as class A [i.e. with heroin and crack cocaine]". Alan Johnson will doubtless have seen the same MORI survey results.

Yet New Labour has a further reason beyond mere opinion-poll tracking, for taking the line it has. It was Tony Blair's intuition that the Labour Party could never win the key electoral battle ground known as "middle England" without wiping out the widespread view that it was a party of bearded student lecturers, hostile to the armed forces, soft on crime and – well, basically, a load of ex-Commies. Blair set his party's cap at what was called "Mondeo man", thought to be a middle manager in marketing who read the Daily Mail. Above all, New Labour never, ever wanted to be "out-toughed" by the Tories.

This was clearest of all in Blair's attempts to introduce 90 days' detention without charge for "terrorist suspects", in essence abolishing habeas corpus. None of the intelligence or security services had demanded such a dramatic extension of the arbitrary power of the state over the liberty of the person, but Blair knew that it would get the dreamed-of Sun headline "Labour gets tough on terror". In every sense, it was putting politics before justice and the evidence. At a Parliamentary Labour Party meeting before the vote on "90 days", Blair shamelessly told his MPs that a primary purpose of the legislation was to split the Tories, many of whom have what he would have regarded as a quaintly old-fashioned view about liberty and the rights of the individual.

That vote was lost, fortunately; but as soon as Gordon Brown became leader, he decided to replay this base political stunt of looking "tougher than the Tories" on terror, by introducing a bill proposing 42 days detention without charge – even though the current 28 days is longer than anywhere else in the civilised world. Again, the relevant experts – led in this case by the former MI5 chief Eliza Manningham-Buller – pointed out that this would promote more trouble than safety; but just as with its blocking out of Professor Nutt and his colleagues at the Advisory Council on the Misuse of Drugs, New Labour was only interested in the political points to be scored, rather than the objective demands of rational policy formation. After all, if Alan Johnson were truly interested in the arguments about the risks of drugs, and therefore where the criminal law should bear lightly and where heavily, he would now be giving a detailed exposition of why, having earlier downgraded cannabis to class C in 2004 the Home Office then upgraded it to B. What evidence changed, between 2004 and now?

One thing that did happen was that David Cameron, though not thought to be personally unfamiliar with recreational drug-taking in his student days, had repeatedly harangued Gordon Brown to reclassify cannabis as a class B drug (and thus increasing the possible maximum prison sentence on conviction for use, from two years to five years). Mr Cameron said that Mr Brown should "stop dithering" and reclassify the drug – and like all ditherers, if there's one thing Brown can not stand, it's being called a ditherer.

David Cameron apart, it would be interesting to know how many MPs, on all sides of the House, would now have criminal records if the police had discovered them smoking cannabis while in their student days. Jacqui Smith would, by her own admission. Put your sledgehammer away, Mr Johnson: it's making you look ridiculous.

d.lawson@independent.co.uk