SECTION 1. Chapter 150E, section 9 is hereby amended by replacing the 9th paragraph with the following language:—Upon the filing of a petition pursuant to this section for a determination of an impasse or the filing of a petition for exercise of jurisdiction of the Joint Labor Management Committee under St. 1973, c. 1078 following interim negotiations or negotiations for a successor agreement, an employer shall not implement unilateral changes until the collective bargaining process, including mediation, fact finding or arbitration, if applicable, shall have been completed and the terms and conditions of employment shall continue in effect until the collective bargaining process, including mediation, fact finding or arbitration, if applicable, shall have been completed; provided, however, that nothing contained herein shall prohibit the parties from extending the terms and conditions of such a collective bargaining agreement by mutual agreement for a period of time in excess of the aforementioned time. For purposes of this paragraph, the board or the Joint Labor Management Committee shall certify to the parties that the collective bargaining process, including mediation, fact finding or arbitration, if applicable, has been completed.