California Code, Public Utilities Code - PUC § 102403

If there is a question whether an employee organization represents a majority of employees or whether the proposed unit is or is not appropriate, such matters shall be submitted to the California State Mediation and Conciliation Service for disposition.  The California State Mediation and Conciliation Service shall promptly hold a public hearing after due notice to all interested parties and shall thereupon determine the unit appropriate for the purposes of collective bargaining.  In making such determination and in establishing rules and regulations governing petitions and the conduct of hearings and elections, the California State Mediation and Conciliation Service shall be guided by relevant federal law and administrative practice, developed under the Labor-Management Relations Act, 1947, as presently amended.  1  It is declared to be in the public interest that the district shall not express any preference for one union over another.

The California State Mediation and Conciliation Service shall provide for an election to determine the question of representation and shall certify the results to the parties.  Any certification of an employee organization to represent or act for the employees in any collective bargaining unit shall not be subject to challenge on the grounds that a new substantial question of representation within such collective bargaining unit exists until the lapse of one year from the date of certification or the expiration of any collective bargaining agreement, whichever is later; provided, that no collective bargaining agreement shall be construed to be a bar to representation proceedings for a period of more than two years.