Mass. Gen. Laws ch. 152, § 48
(2) When the insurer and the employee reach such agreement subsequent to insurer acceptance of liability or subsequent to a decision of an administrative judge, the reviewing board, or an appeals court of the commonwealth finding insurer liability which decision is in effect at the time such agreement is entered into, said agreement shall not redeem liability for the payment of medical benefits or vocational rehabilitation benefits with respect to such injury.
No lump sum agreement made prior to the establishment of liability for compensation shall prohibit an employee from subsequently filing a claim for medical benefits only, in any instance in which such employee has suffered a substantial deterioration of his medical condition which (i) could not reasonably have been foreseen at the time said agreement was entered into, and (ii) is the result of an injury for which the insurer would have been liable under this chapter, absent the lump sum settlement. Claims under this paragraph shall be considered only if brought within one year of the date the employee first became aware of the causal relationship between the substantial deterioration and the employment. Claims shall be consistent with the procedures set forth in sections ten, ten A, and eleven. No liability for such claims shall be redeemed by any additional lump sum settlement; provided, however, that no employee shall be entitled to vocational rehabilitation benefits for any injury, unless such employee shall have requested such benefits within two years of the perfection of any settlement under this section of benefits due for said injury.
(4) Whenever a lump sum agreement has been perfected in accordance with the terms of this section, such agreement shall affect only the insurer and the employee who are parties to such lump sum agreement and shall not affect any other action or proceeding arising out of a separate and distinct injury under this chapter, whether the injury precedes or arises subsequent to the date of settlement, and whether or not the same insurer is claimed to be liable for such separate and distinct injury.
Notwithstanding any provision of this section or of sections seventy-five A or seventy-five B, the acceptance of any amount in return for the right to claim future weekly benefits shall create a presumption that the employee is physically incapable of returning to work with the employer where the alleged injury occurred. Such presumption shall continue for a period of one month for each fifteen hundred dollar amount included in the settlement for future weekly benefits. No re-employment rights shall inure to such employee under this chapter during any period of presumption of incapacity as herein provided.