When Colorado and Washington state each passed ballot measures legalizing marijuana for recreational use late last year, one legal challenge was resolved, but another was just beginning Before, marijuana was simply prohibited. Now it has to be regulated. With their new legal standards for possession and use, Colorado and Washington now have to draw hard lines on a rather hazy landscape, creating legal standards not just for for taxation and licensing, but also some far more nebulous questions, like how much marijuana is reasonable for a single person to possess, and even what constitutes legal intoxication. Meanwhile, forty-eight other states are watching closely to see exactly how they do it.