"As far as I know, ironically, there is no law that prohibits smoking marijuana."
smoking is the verb, marijuana is the noun, and the object of the verb. Possession of this object is predicated on the verb.
it is not illegal to smoke (or eat) banana peels, and none ever claimed it was. Thus, you initial premise "the Liberteens paint an entirely different picture. They claim that HUNDREDS of THOUSANDS are behind bars for smoking."
is just silly. Not true, never happened, and is whats known as a "straw-man argument".
Wanna try again? Please don't... that was lame.
The question is - Has ANYONE ever been imprisoned for smoking pot?
Do you have an answer? (Careful - the entire Liberteen society hinges on your opinion...)