California Code, Family Code - FAM § 354

(a) Each applicant for a marriage license shall be required to present authentic photo identification acceptable to the county clerk as to name and date of birth.A credible witness affidavit or affidavits may be used in lieu of authentic photo identification.

(b) For the purpose of ascertaining the facts mentioned or required in this part, if the clerk deems it necessary, the clerk may examine the applicants for a marriage license on oath at the time of the application. The clerk shall reduce the examination to writing and the applicants shall sign it.

(c) If necessary, the clerk may request additional documentary proof as to the accuracy of the facts stated.

(d) Applicants for a marriage license shall not be required to state, for any purpose, their race or color.

(e) If a marriage is to be entered into pursuant to subdivision (b) of Section 420, the attorney in fact shall comply with the requirements of this section on behalf of the applicant who is overseas, if necessary.