If a person authorized to make an arrest shall have probable cause to believe that a misdemeanor for which he may make an arrest is being committed in his presence, such probable cause shall be a defence in an action brought against him for false arrest or imprisonment.
Mass. Gen. Laws ch. 231, § 94A
Probable cause as defence in action for false arrest
Official source: Massachusetts Legislature. Reproduced from public-domain Massachusetts statutes; confirm against the official source for the current text. Not legal advice.