Oh for crying out loud, call it a kind of cigarette, slap some 'don't do it at work/while driving/don't sell it to minors' restrictions with similar penalties to alcohol and be done with it.
It smells and stoned folks can be annoying, but it's not like booze- nobody is going to OD and die or get violent or something. Keep it out of kids hands as best you can (best of luck with that, but try) and get on with life.