This article in (UK newspaper) The Guardian refers to the views of David Nutt, an Imperial College professor, a government adviser appointed by the government, and then ignored. There was a time when British politicians were taking about evidence bases policy, here is the evidence that has been ignored.
(more detail in this article by Nutt,’Estimating drugs harms: a risky business?, link leads to pdf. Amongst other things, Nutt points out the damage caused by ‘skunk’, strong cannabis, is grossly exaggerated.)
30 People die a year from ecstasy, 100 people a year die from horse riding accidents.
Alcohol is the 5th most harmful drug, ahead of heroin, cocaine, barbiturates and methadone.
We could stop one case of schizophrenia, if we prevent 5 000 men aged between 20 and 25 from ever taking cannabis, i.e. the risk of mental illness from using cannabis is very small.
On a personal note I don’t find drugs other than alcohol attractive, and people who claim to have their mind expanded by drugs bore me, but the number of people harmed by alcohol far exceeds those harmed by illegal substances.
The issues raised here are not simply those of drugs policy, they refer to the role of reason and evidence in politics, and public policy, and disturbing evidence of their lack in those fields.