Those who enthusiastically urge the decriminalisation of possessing and growing cannabis – in Australia primarily the Green Party – are engaging in an unethical advocacy. It is just far too risky.
The Independent argues that, in the UK, modern forms of cannabis are unambiguously linked to psychosis and to addiction. The evidence in Australia for increasing levels of addiction to high strength cannabis and of a link with psychosis is strong. As I have argued in the past, the causality of the link with psychosis is questionable but it certainly can trigger psychosis among those predisposed and it is particularly dangerous among teenagers (and here). On the basis of a sensible precautionary principle, cannabis use should not be legalised - if you foolishly do wish to use it at least wait until you reach age 25+.
As The Independent remarks, in the UK ‘More than 22,000 people were treated last year for cannabis addiction - and almost half of those affected were under 18’. ‘Robin Murray, professor of psychiatry at London's Institute of Psychiatry, estimates that at least 25,000 of the 250,000 schizophrenics in the UK could have avoided the illness if they had not used cannabis.’
A major study is about to appear in The Lancet supporting this analysis. The Independent’s article was an apology for its campaign over the past 10 years to legalise cannabis.