I need Family advice?

There has been lot going on this last few years. My mom and step-dad are separated looking at a divorce. As of right now, it is my 18 yr old sister, 15 yr old brother, my mom and I living together (I am 22). I just moved back in like 3 weeks ago. I guess my main question is how to talk to my mom about my brother smoking pot. I have been in his situation, and I understand where he is coming from. I know that it is illegal, but he stays at home, and doesn't get into any trouble. I am trying to help my mom understand how he feels. I know pot isn't the answer to everything, but it is working for him right now. He is very mature and goes to school and doesn't ditch. Please don't answer if you are going to be an asshole, I am just trying to help be a Dr. Phil in a needed situation. ThanksI need Family advice?
what i suggest is when everyone else is out (e.g. school) or at least your brother, ask her if you can talk about it in private.I need Family advice?
keep trying your best and everything will work out
I hope your mom grounds his little rear and sends him to rehab. You are making excuses for him instead of forcing him to face his problems or take his drugs away. He is not mature, he is an idiot throwing his life away for a high. Your mom will not understand why he does it.