Is it illegal to physically restrain your 15 yr old son for his own safety?

Our son is 15 and has been in & out of foster & group homes because of behavioral issues. He has run away constantly; he has smoked pot & drank alcohol since he was 8; he has experimented with Methanphetamines & Cocaine; he is sexually active. He doesn't go to school, refuses to do family therapy & has threatened to physically harm his father & won't obey ANYBODY's rules! So, I believe his dad & I need to be really radical with him. He also wants to grow & sell marijuana, which his father & I are totally against! I need to know is it illegal, in California, to physically restrain our son to protect him from his out-of-control behaviors & to try to force therapy on him so later in his life, the cops won't be forced to use billy clubs on him????