California Code, Government Code - GOV § 19587

If the petition for rehearing is granted, the matter shall be set down for rehearing by the board or its authorized representative.  If the matter is set for hearing before an authorized representative, the hearing shall be conducted as to the matters on which granted in substantially the same manner and under like rules of procedure as an original hearing upon charges under this article.  If the matter is set for hearing before the board itself, the board may provide the parties with an opportunity to provide written or oral argument and may decide the case upon the record, including the transcript, with or without taking additional evidence.