Sorry Avoice

I remember being 22 and wish I knew about my ADD back then. ADD is a monster that I've always fought. I was lucky because I always seemed to have people in my life that would "Draw the line" and have boundries set for me that were absolute. I never liked them, thought they were unfair, but the structure they provided kept me "In Check" and forced me to do the right things (Most of the time). I can see this in my daughters now. They do much better when they are in school, pushed by tough classes, pushed by us at home (Regarding homework/projects).
I know it must be very hard, especially because you have had plenty of your own to deal with too. Maybe a "No Smoking" policy, period? You don't need to discuss K2 being legal or not, ADDer's love to argue (Some of us at least) because it wakes them up, gives them a purpose.
I hope you can find a way to get him the "Kick in the Pants" that he needs