Legal Question in Family Law in California

It depends on whether he is on legal record as the father. Either he and the mother must have signed a joint voluntary declaration of paternity when the baby was born, or there must have been a court determination that he is the father. If neither of those have been done, then he needs to start the court proceeding to be declared legally the father, and in that same case he can ask for immediate temporary custody. If he is already the legal father, he can just take her, but not if there is risk of significant altercation or violence. If that is a risk, he should take the papers that show he is the legal father to the police and get their assistance in recovering the child.