California Code, Public Utilities Code - PUC § 40122

If there is a question whether a labor organization represents a majority of employees or whether the proposed unit is or is not appropriate, such matters shall be submitted to the State Conciliation Service for disposition.  The State 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, the conduct of hearings and elections, the State Conciliation Service shall be guided by relevant federal law and administrative practice, developed under the Labor-Management Relations Act, 1947, as presently amended.  1

The State Conciliation Service shall provide for an election to determine the question of representation and shall certify the results to the parties.  Any certification of a labor 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.