Car Seat Guidelines

I’m not trying to be picky or nit pick over this subject, but my child’s father refuses to turn his car seat rear-facing when he is in his care, and he never buckles him in completely. My son is 16 months old, and the law requires that he has to be rear-facing until he’s at least 2. I fear for him when he’s away with him, so can anyone offer any advice as to what I can do? Get the police involved, or something because he refuses to listen to me.