It is a crime to impersonate a police officer, or other peace officer or investigative officer.
Simply put, you can’t claim you are a police officer “and act as such” by using the authority of your position to attempt to compel someone to assist you “in a manner pertaining to the duty of such officer”.
That doesn’t mean you can’t dress up like a police officer at a Halloween party. Impersonation requires an affirmative action, claim or request in a circumstance or situation where someone might believe you are that official.
According to Chapter 268, Section 33 of the Massachusetts criminal statutes, it applies to a wide variety of public inspectors, constables, examiners, or investigators.
Penalties for Impersonation a Police Officer
The penalty is up to a year in jail and a $400 fine.