Mass. Gen. Laws ch. 161A, § 28
Notwithstanding the provisions of sections 25 and 26, the authority or any organizations representing employees of the authority shall not be permitted to submit any dispute over the terms of a collective bargaining agreement to arbitration except in accordance with sections 28 through 32, inclusive; provided, however, that this section shall not limit the rights of organizations representing employees of the authority to submit grievances to arbitration in accordance with the collective bargaining agreement between the parties.