(Were you really being serious?)
For countries which have implemented this proposal or slightly watered down versions: see Singapore and China and note that even though they are in the middle of a drug heavy region, they have still managed to keep their countries relatively drug free.
As various other commenters have pointed out, between prescriptions, over-the-counter pills, vitamins, and additives in the foods we buy, we're all drug users. This whole argument seems to rest upon an absolutist view that all currently illegal drugs are absolutely destructive and have no merit.
Countries like Singapore and China have radically different ideological approaches to policy than most Western nations. They are comfortable enforcing absolutist positions that limit individual freedoms. Such a position is against America's founding principles. They may statistically report less drug use, but is their society actually any better off for it?
Now they are taking big risks and I wouldn't take those kind of risk if I were them but it convinced me that however strict the laws are against drug it doesn't stop people from taking them...