Cal. Government Code § 31807

The retirement allowance payable under Section 31808, Section 31808.1 or Section 31809 of this code, whichever is applicable, to a person who was a member on the effective date of this article in any county pursuant to this article if not fully insured for old age payments under the federal system at time of retirement shall be not less than that amount for which he would have been eligible if this article were not applicable to the member. The retirement allowance payable under Section 31808, Section 31808.1 or Section 31809 of this code, whichever is applicable, to a person who was a member on the effective date of this article in any county pursuant to this article if fully insured for old age payments under the federal system at time of retirement shall not be less than an amount which, when added to the primary insurance amount payable to him under the federal system at time of retirement will equal the allowance which would otherwise be payable to the member under the provisions of this chapter if this article were not applicable to the member. If the member retires for service prior to retirement age under the federal system and the amount available to him under the provisions of Section 31810 is less than the allowance which would otherwise be payable to the member under the provisions of this chapter if this article were not applicable to the member then the allowance shall be increased to an amount not less than that which would otherwise be payable.