"Drug harms in the UK: a multi-criteria decision analysis", by David Nutt, Leslie King and Lawrence Phillips, on behalf of the Independent Scientific Committee on Drugs. 
The Lancet.
And yet and yet discussion of drugs and how to treat them is taboo
No British politician will touch the subject let alone suggest moving away from the current 'drugs are evil lock 'em up approach', which demonstratively has not worked and is not working.
Just another British 'ostrich' subject.