California Code, Code of Civil Procedure - CCP § 1299.5

(a) The arbitration panel shall, within 10 days after its establishment or any additional periods to which the parties agree, meet with the parties or their representatives, either jointly or separately, make inquiries and investigations, hold hearings, and take any other action including further mediation, that the arbitration panel deems appropriate.

(b) For the purpose of its hearings, investigations, or inquiries, the arbitration panel may subpoena witnesses, administer oaths, take the testimony of any person, and issue subpoenas duces tecum to require the production and examination of any employer's or employee organization's records, books, or papers relating to any subject matter before the panel.