California Code, Penal Code - PEN § 679.015

(a) It is the public policy of this state to protect the public from crime and violence by encouraging all persons who are victims of or witnesses to crimes, or who otherwise can give evidence in a criminal investigation, to cooperate with the criminal justice system and not to penalize these persons for being victims or for cooperating with the criminal justice system.

(b) Whenever an individual who is a victim of or witness to a crime, or who otherwise can give evidence in a criminal investigation, is not charged with or convicted of committing any crime under state law, a peace officer may not detain the individual exclusively for any actual or suspected immigration violation or turn the individual over to federal immigration authorities absent a judicial warrant.