Can you change your name on a California driver's license using a same-sex marriage certificate?

Yes. A person in a civil union or same-sex marriage may use their certificate of civil union or of marriage as proof of legal name change for the purpose of obtaining a Colorado driver's license in their new name. There is an extra step in Colorado, that is not typical in other states, wherein the applicant must first register their civil union or marriage certificate with the clerk of the county in which the applicant resides.