Do they put you in jail in Chicago for just carrying a beer? Or is it that they put you in jail for public intoxication, which of course they could do no matter what substance you were intoxicated on? I think you have to distinguish between mere possession, consuming the substance in public, and public intoxication. There are important differences between the three. It does make sense in many cases to arrest people for public intoxication who are either dangerous or just a real annoyance to the public. Simple possession while one is in public does not warrant an arrest. As for consuming in public, I guess it depends on the circumstances. It seems like a ticket and confiscation, if that, would be enough in most cases.
Frankly, I'd like to see them completely decriminalize possession, and then attach a felony penalty with mandatory jail time to *transfer* of *any* amount for *any* reason, and to commission of *any* crime while under the influence.
I.e., you can have all you want, and get as stoned and stupid as you want, but you get caught giving it to someone else - even your wife or kids - or do something stupid to somebody *else* as a result of your little "experimentation", and You're Going Away, Hippie.
My major reason for proposing this is the screams of outraged frustration that it would provoke among the potheads. It would be a delectable case of "be careful what you ask for, you might get it."
But NTS, I'm not holding my breath...