Trying to help a friend

Okay so my friend’s parents split up a while ago and his mom as full custody of all three kids she and his dad have. He still gets to see them once in a while but not very often. The court ordered that she not drink an alcohol while she has the kids however, she drinks very often. My friend gets really upset when she drinks and says she no longer has any time for him or his siblings. She lets them do whatever they want and doesn’t really care if they’re acting out. He’s not doing well at his house and he has tried to stay with friends for a while but she won’t let him. He has also told her that he wants to stay with his dad but she refuses to let him do that due to the fact that she has full custody. I was wondering if there was something my friend could do about his situation. He’s 16 and he has reasons as to why he would rather be with his dad not to mention his mom is breaking the court ruling.