CA Gov't Code Section 3544.3

If, by January 1 of any school year, no employee organization has made a claim of majority support in an appropriate unit pursuant to Section 3544, a majority of employees of an appropriate unit may submit to a public school employer a petition signed by at least a majority of the employees in the appropriate unit requesting a representation election. An employee may sign such a petition though not a member of any employee organization. Upon the filing of such a petition, the public school employer shall immediately post a notice of such request upon all employee bulletin boards at each school or other facility in which members of the unit claimed to be appropriate are employed. Any employee organization shall have the right to appear on the ballot if, within 15 workdays after the posting of such notice, it makes the showing of interest required by subdivision (b) of Section 3544.1. Immediately upon expiration of the 15-workday period following the posting of the notice, the public school employer shall transmit to the board the petition and the names of all employee organizations that have the right to appear on the ballot.