California Code, Family Code - FAM § 217

(a) At a hearing on any order to show cause or notice of motion brought pursuant to this code, absent a stipulation of the parties or a finding of good cause pursuant to subdivision (b), the court shall receive any live, competent testimony that is relevant and within the scope of the hearing and the court may ask questions of the parties.

(b) In appropriate cases, a court may make a finding of good cause to refuse to receive live testimony and shall state its reasons for the finding on the record or in writing. The Judicial Council shall, by January 1, 2012, adopt a statewide rule of court regarding the factors a court shall consider in making a finding of good cause.

(c) A party seeking to present live testimony from witnesses other than the parties shall, prior to the hearing, file and serve a witness list with a brief description of the anticipated testimony. If the witness list is not served prior to the hearing, the court may, on request, grant a brief continuance and may make appropriate temporary orders pending the continued hearing.