California Code, Insurance Code - INS § 4016.2

(a) The presence in person or by proxy of 5 percent of the members of a domestic mutual insurer entitled to vote at any meeting shall constitute a quorum for the transaction of all business of the insurer, including but not limited to, the amendment of the articles of incorporation or bylaws of the insurer, unless otherwise provided in the articles of incorporation or bylaws of such insurer.

(b) Any required member approval shall be by the affirmative vote of a number of members which, as to a stock corporation, would constitute approval of the shareholders (Section 153 of the Corporations Code) rather than approval of the outstanding shares (Section 152 of the Corporations Code).