CA Rev & Tax Code Section 1605.4

Equalization hearings shall be open and public except that, upon conclusion of the taking of evidence, the county board may deliberate in private in reaching a decision. An applicant may request the board to close to the public a portion of the hearing by filing a declaration under penalty of perjury that evidence is to be presented which relates to trade secrets the disclosure of which will be detrimental to the business interests of the owner of the trade secrets. If the board grants the request, only evidence relating to the trade secrets may be presented during the time the hearing is closed.