I would argue, from a pure cost-benefit perspective that full legalization of drugs is desirable unless someone has another credible plan for eliminating the black market without unacceptable consequences (e.g. a police state).

What's needed is evidence based approach, where wt draw a line at alcohol and all drugs less lethal/ addictive/ harmful (take your pick) are legalised.

There are some truly horrible substances, but with current approach heroin and weed are sold by the same guy.