Cal. Labor Code § 115

Actions of the appeals board shall be taken by decision of a majority of the appeals board except as otherwise expressly provided. The chairman shall assign pending cases in which reconsideration is sought to any three members thereof for hearing, consideration and decision. Assignments by the chairman of members to such cases shall be rotated on a case-by-case basis with the composition of the members so assigned being varied and changed to assure that there shall never be a fixed and continued composition of members. Any such case assigned to any three members in which the finding, order, decision or award is made and filed by any two or more of such members shall be the action of the appeals board unless reconsideration is had in accordance with the provisions of Article 1 (commencing with Section 5900), Chapter 7, Part 4, Division 4 of this code. Any case assigned to three members shall be heard and decided only by them, unless the matter has been reassigned by the chairman on a majority vote of the appeals board to the appeals board as a whole in order to achieve uniformity of decision, or in cases presenting novel issues.