No one should be charged with a crime for drug use of any kind. Ever.
But I don't suggest that all of these drugs be legally available. Knowingly selling some of the most addictive and destructive of these substances should be criminal. End the War on Drugs and make those who profit from this social problem pay for the public health crisis that they selfishly create.
Presumably you feel the same way about Tobacco, and to a lesser extent, Alcohol companies?
The most used "illicit" drug, Marijuana, is less destructive than Alcohol and less addictive than Nicotine (and about the same as Alcohol). Arguably the health effects are less severe than in Nicotine, but I want to see more studies before I am comfortable saying that. Let's legalize Marijuana and really study it's effects, good and bad.
As for Alcohol, I got two words for you, Hepatic Cirrhosis.
Yeah alcoholism is a very bad thing man.
I just read the wikipedia article on Hepatic Cirrhosis and now I have to say:
Man, it's time to stay away from the alcohol.