Hello, I am also new to this board. Just had to get that out of the way..
But Polaris, when I was around the age of 15, I got caught with weed at school and was in sort of the same situation your son is in. My home life was fucked up but after i got arrested i went to a "rehab" center and cut down on my smoking. I still smoke today and have a great family life and am doing good in school. So what im saying is get him some help and let him see the bad shit that can happen from unresponsible pot smoking and he may relise that other things should come before weed.