Isn't this an interesting little assertion from one of the government's own reports?

Decriminalising drugs would have little effect on the number of people abusing illegal substances, a highly controversial Home Office report has said. ... The report – which sources said had caused “panic” within the Home Office – said: “There are indications that decriminalisation can reduce the burden on criminal justice systems.

“It is not clear that decriminalisation has an impact on levels of drug use.

"The disparity in drug use trends and criminal justice statistics between countries with similar approaches, and the lack of any clear correlation between the ‘toughness’ of an approach and levels of drug use demonstrates the complexity of the issue."

The point being, and this can be readily verified by anyone with even the most modest experience of social life in Britain, that all those who want to consume drugs are currently easily able to find the drugs they wish to consume. Meaning that the illegality isn't particularly affecting the availability of supply. Thus decriminalisation seems like a good idea as it's not going to lead to half the population toking itself into a stupor.

However, that decriminalisation isn't enough as we've mentioned around here before. For the major danger of drugs comes not from they themselves, but from the fact that purity and concentration are, given that they are illegal products, entirely unknown to the user. Overdosing is thus depressingly commonplace, as are all sorts of diseases and illnesses from the admixtures. Thus we need to be thinking very seriously about legalisation: not just decriminalisation of small amounts for personal use but the legalisation of supply and production. For that is how we would get brands, reliant upon their quality and consistency, and also get a transparent supply network that can be checked for quality.

It's not just the criminality of taking drugs that is causing our current problems, it's the illegality of supply as well.