California Code, Revenue and Taxation Code - RTC § 1624.2

No member of an assessment appeals board shall knowingly participate in any assessment appeal proceeding wherein the member has an interest in either the subject matter of or a party to the proceeding of such nature that it could reasonably be expected to influence the impartiality of his judgment in the proceeding. Violation of this section shall be cause for removal under Section 1625 of this code.