Except as provided in sections 331, 364, 604, 653.5, 654, and 655, the social worker or probation officer has the sole discretion to determine whether to file a petition under section 300 and 601. The prosecuting attorney has the sole discretion to file a petition under section 602.
A proceeding in juvenile court to declare a child a dependent or a ward of the court is commenced by the filing of a petition.
Any person may apply to the social worker or probation officer to commence proceedings. The application must be in the form of an affidavit alleging facts showing the child is described in sections 300, 601, or 602. The social worker or probation officer must proceed under sections 329, 653, or 653.5. The applicant may seek review of a decision not to file a petition by proceeding under section 331 or 655.
Cal. R. Ct. 5.520