Unless otherwise agreed by the parties, if a party so requests or if the arbitral tribunal considers it necessary, the expert shall, after delivery of his or her written or oral report, participate in an oral hearing where the parties have the opportunity to question the expert and to present expert witnesses on the points at issue.
Source:
Section 1297.262, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=CCP§ionNum=1297.262..