Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 6E, § 15

(a) An officer present and observing another officer using physical force, including deadly force, beyond that which is necessary or objectively reasonable based on the totality of the circumstances, shall intervene to prevent the use of unreasonable force unless intervening would result in imminent harm to the officer or another identifiable individual.

(b) An officer who observes another officer using physical force, including deadly force, beyond that which is necessary or objectively reasonable based on the totality of the circumstances shall report the incident to an appropriate supervisor as soon as reasonably possible but not later than the end of the officer’s shift. The officer shall prepare a detailed written statement describing the incident consistent with uniform protocols. The officer’s written statement shall be included in the supervisor’s report.

(c) A law enforcement agency shall develop and implement a policy and procedure for law enforcement personnel to report abuse by other law enforcement personnel without fear of retaliation or actual retaliation.

(d) The commission and the municipal police training committee established pursuant to section 116 of chapter 6 shall jointly promulgate rules and regulations for the use of force by law enforcement officers consistent with this section and section 14; provided, however, that such regulations may authorize the use of necessary, proportionate and non-deadly force for purposes not explicitly specified in this chapter where de-escalation tactics have been attempted and failed or are not feasible based on the totality of the circumstances.