Welf. & Inst. Code, § 777

An order changing or modifying a previous order by removing a minor from the physical custody of a parent, guardian, relative, or friend and directing placement in a foster home, or commitment to a private institution or commitment to a county institution, or an order changing or modifying a previous order by directing commitment to the Youth Authority shall be made only after a noticed hearing.

(a) The notice shall be made as follows:

(1) By the probation officer where a minor has been declared a ward of the court or a probationer under Section 601 in the original matter and shall contain a concise statement of facts sufficient to support the conclusion that the minor has violated an order of the court.

(2) By the probation officer or the prosecuting attorney if the minor is a court ward or probationer under Section 602 in the original matter and the notice alleges a violation of a condition of probation not amounting to a crime. The notice shall contain a concise statement of facts sufficient to support this conclusion.

(3) Where the probation officer is the petitioner pursuant to paragraph (2), prior to the attachment of jeopardy at the time of the jurisdictional hearing, the prosecuting attorney may make a motion to dismiss the notice and may request that the matter be referred to the probation officer for whatever action the prosecuting or probation officer may deem appropriate.

(b) Upon the filing of such notice, the clerk of the juvenile court shall immediately set the same for hearing within 30 days, and the probation officer shall cause notice of it to be served upon the persons and in the manner prescribed by Sections 658 and 660. Service under this subdivision may be by electronic service pursuant to Section 212.5.

(c) The facts alleged in the notice shall be established by a preponderance of the evidence at a hearing to change, modify, or set aside a previous order. The court may admit and consider reliable hearsay evidence at the hearing to the same extent that such evidence would be admissible in an adult probation revocation hearing, pursuant to the decision in People v. Brown, 215 Cal.App.3d (1989) and any other relevant provision of law.

(d) An order for the detention of the minor pending adjudication of the alleged violation may be made only after a hearing is conducted pursuant to Article 15 (commencing with Section 625) of this chapter. Service under this subdivision may be by electronic service pursuant to Section 212.5, but only in addition to other forms of service required by law.