California Code, Elections Code - ELEC § 9044

If an argument for or an argument against a measure submitted to the voters by the Legislature has not been filed by a Member of the Legislature, any voter may request the Secretary of State's permission to prepare and file an argument for either side, on which no argument has been prepared by a Member of the Legislature. The Secretary of State shall grant permission unless two or more voters request permission to submit arguments on the same side of a measure, in which event the Secretary of State shall designate one of the voters to write the argument. Any argument prepared pursuant to this section shall be submitted to the Secretary of State by a date sufficient to meet ballot printing deadlines.