I've moved about ten years ago into the "legalize it all" camp.  I can't imagine folks who are not doing heroin now suddenly running to the store to try it, and the people using it aren't having any problem finding it, now.

Just the three basic economic benefits are overwhelming, hard to imagine we couldn't do more good with that than all current efforts combined:

o  Save billions on law enforcement.
  -  cops, jails, courts...
  -  Drug dealers and gangs buying guns with drug money?  Gone.

o  Tax drugs.
  -  billions in direct revenue

o  Keep users working.
  -  Most drug users have jobs and families.  Putting them in jail halts all tax revenue and drives up social assistance costs massively.

William F Buckley - of all people - got me started down this path with a guest on his show long ago who had done historical research and found that no society in all of human history has notably decreased drug use.  When a society does a great deal to discourage drug use, he fixed percentage that do use drugs tend to cause more harm to themselves and society (harder/weirder drugs, more crime attached...).  The Netherlands had (last I looked) an aging population of native heroin users - by just less than a year for each year since drug laws were changed - iow there were not many new addicts, and those who already were are aging.  More teens looking for a drug experience just smoke pot, less go as far as heroin.

It would be great if everyone ate wheaties, jogged, drank green tea and did yoga.  However, since that isn't going to happen, not making an inevitable situation much much much worse would be a really good start.

Besides, the very idea of gov't being interested in its citizens body chemistry is a bit spooky.  Legislate actions, the reason for those actions is largely immaterial (crash a car?  tired/stoned/stupid - don't really care - your actions have consequences...).