Section 9. After a reasonable period of negotiation over the terms of a collective bargaining agreement, either party or the parties acting jointly may petition the board for a determination of the existence of an impasse. Upon receipt of such petition, the board shall commence an investigation forthwith to determine if the parties have negotiated for a reasonable period of time and if an impasse exists, within ten days of the receipt of such petition, the board shall notify the parties of the results of its investigation. Failure to notify the parties within ten days shall be taken to mean that an impasse exists.

Within five days after such determination, the board shall appoint a mediator to assist the parties in the resolution of the impasse. In the alternative, the parties may agree upon a person to serve as a mediator and shall notify the board of such agreement and choice of mediator. Any such mediator shall be empowered to order the parties to provide specific representatives authorized to enter into a collective bargaining agreement to be present at meetings held for said purpose of resolving the impasse and negotiating such an agreement.

After a reasonable period of mediation from the date of appointment, said mediator shall issue to the board a report indicating the results of his services in resolving the impasse.

If the impasse continues after the conclusion of mediation, either party or the parties acting jointly may petition the board to initiate fact-finding proceedings. Upon receipt of such petition, the board shall appoint a fact-finder, representative of the public, from a list of qualified persons maintained by the board. In the alternative, the parties may agree upon a person to serve as fact-finder and shall notify the board of such agreement and choice of fact-finder. No person shall be named as a fact-finder who has represented an employer or employee organization within the preceding twelve months. The fact-finder shall be subject to the rules of the board and shall, in addition to powers delegated to him by the board, have the power to mediate and to make recommendations for the resolution of the impasse. The fact-finder shall transmit his findings and any recommendations for the resolution of the impasse to the board and to both parties within thirty days after the record is closed. If the impasse remains unresolved ten days after the transmittal of such findings and recommendations, the board shall make them public.

The parties by their own agreement may mutually waive the fact-finding provisions contained herein and may petition the board for arbitration pursuant to sections four or four B of chapter one thousand and seventy-eight of the acts of nineteen hundred and seventy-three when applicable. Said waiver shall not constitute a bar to any arbitration award.

Any arbitration award in a proceeding voluntarily agreed to by the parties to resolve an impasse shall be binding on the parties and on the appropriate legislative body and made effective and enforceable pursuant to the provisions of chapter one hundred and fifty C, provided that said arbitration proceeding has been authorized by the appropriate legislative body or in the case of school employees, by the appropriate school committee.

If the impasse continues after the publication of the fact-finder's report, the issues in dispute shall be returned to the parties for further bargaining.

Any time limitations prescribed in this section may be extended by mutual agreement of the parties and the board.

Upon the filing of a petition pursuant to this section for a determination of an impasse following 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 shall certify to the parties that the collective bargaining process, including mediation, fact finding or arbitration, if applicable, has been completed.

Any person acting as a mediator in a labor dispute, including any person acting as such pursuant to the provisions of this chapter, who receives information as a mediator relating to the labor dispute shall not be required to reveal such information received by him in the course of mediation in any administrative, civil or arbitration proceeding. Nothing herein contained shall apply to any criminal proceedings.