Cal. Fam. Code § 3088 : CALIFORNIA FAMILY CODE — CUSTODY OF CHILDREN — RIGHT TO CUSTODY OF MINOR CHILD — JOINT CUSTODY — Order of custody modified to order for joint custody

An order for the custody of a minor child entered by a court in this state or any other state may, subject to the jurisdictional requirements in Sections 3403 and 3414, be modified at any time to an order for joint custody in accordance with this chapter.