Mistake. Those drugs are dangerous.
And keeping them criminalized, which results in a black market, competition for territory, lack of adequate treatment, and increased crime is a better policy?
I wouldn't legalize murder-for-hire just to put the deed out in the open, either.
We need to get people off dangerous drugs. Marijuana is one thing. Heroin? Meth? Cocaine?
We should be focusing on rehabilitation in non-penal settings as we can do with alcohol. Yes, punish the pushers, but lighten up on the addicts.
As for opiates -- most opiate abuse is now the result of misuse of prescriptions. Heroin might be treated the same way.
