not just illegal, but unacceptable.

The Liberal Conspiracy blog calls it "evidence-free" policy making. It is certainly a classic example of how drugs policy is made.

In 2004, Cannabis was downgraded from a Class B to a Class C drug, meaning penalties for possession and supply were reduced (though the maximum sentence for supply remained the same) and giving a signal to police to spend less resources on combating the drug. In the years since then, there has been a steady decline in the rate of cannabis use (eg. from 10.8% to 8.2% of people admitting to having used it in the last year). This is consistent with the well-established trend that making drugs illegal tends to increase their use.

Set against this decrease in use was an increase in the strength of cannabis sold and new evidence that cannabis increases the likelihood of schizophrenia and other mental illnesses. This, and a media campaign which included not just the usual right-wing tirades, but the Independent dramatically reversing its formerly liberal position.

The government commissioned the Advisory Committee on the Misuse of Drugs to produce a report, as it is required to do whenever it wants to change the law. Among the ACMD's conclusions were:

Although there is a consistent (though weak) association, from longitudinal studies, between cannabis use and the development of psychotic illness, this is not reflected in the available evidence on the incidence of psychotic conditions. The most likely (but not the only) explanation is that cannabis – in the population as a whole – plays only a modest role in the development of these conditions. The possibility that the greater use of cannabis preparations with a higher THC content might increase the harmfulness of cannabis to mental health cannot be denied; but the behaviour of cannabis users, in the face of stronger products – as well as the magnitude of a causal association with psychotic illnesses – is uncertain.

Evidence about the social harms associated with cannabis is clearer. Despite public anxieties, there is little real evidence that cannabis is a significant cause of acquisitive crime or of anti-social behaviour. There is, though, cause for concern about the growth of cannabis farms and the emergence of wider organised crime, including people trafficking, that is associated with them.

Decisions about advising on classification must, ultimately, be based on the Council’s collective judgment about the relative harmfulness of substances within, and between, classes. On balance, taking into account the totality of the relevant issues and very mindful of the actual and potential harms, the majority of the Council advises that cannabis and the cannabinols remain in Class C. Although the majority of members recognise the harms caused by the use of cannabis to individuals and society, they do not consider these to be as serious as those of drugs in Class B.

Just to add to this, the police stated reclassification would not change their strategy of "confiscate and warn", freeing up police time for what they consider more serious matters.

Faced with this evidence, the government did not sway from its course, and also decided to throw in some extra new penalties. Carefully cherrypicking from the ACMD's evidence, Home Secretary Jacqui Smith stated "young people may binge on skunk in the same way as alcohol, trying to achieve the maximum effect". Presumably she was oblivious to the implications of comparing the use of cannabis to that of a perfectly legal drug.

According to Gordon Brown, the government needs "to send out a signal that cannabis use was not just illegal but also unacceptable". This may seem like an odd thing to say. Is being unacceptable now a step up from illegal?
On further thought though, this makes sense. After all David Cameron had to specifically state that he knows it's important to obey the law (even though he didn't). Well done David, having mastered the finer points of our legal system you are truly fit to be in charge of it. So if there's the chance that Cameron might be confused about this crucial point, is it any wonder Gordon Brown thinks cannabis users need it making clear to them?

Expect to see a rise in the use of cannabis in the next few years.

(All unreferenced info from the ACMD report into cannabis.)