As a general rule in Massachusetts, the right to use force in defense of oneself or another arises only in circumstances where the person using self-defense avails himself of all proper means to avoid physical combat. However, G.L. c. 278, § 8A represents an exception to this rule. The law provides a defense to the occupant of a dwelling house who is charged with causing injury or death to an intruder. In order to qualify for this affirmative defense, the person charged with injuring or killing the intruder must provide the following three things (1) that he or she reasonably believed that the intruder was unlawfully entering the dwelling, (2) that he or she reasonably believed that the intruder was about to inflict death or serious bodily injury upon the defendant or someone else who is lawfully in the dwelling, and (3) the defendant acted with reasonable means of self-defense or defense of another person who was lawfully present.
When all of the above-listed circumstances are present, under the Massachusetts so-called “castle law,” the homeowner or lawful occupants of the dwelling have absolutely no duty to retreat prior to resorting to self-defense. In summary, the “castle law” relieves a person, otherwise justified in the use of force in self-defense or defense of another, of the duty to retreat (if possible) before resorting to the use of force.
Outside of one’s dwelling, prior to resorting to force in self-defense or the defense of another, there is a duty to retreat if it can be done safely, meaning that retreating would not increase the danger to the person acting in self-defense or another third party. Also, the “castle defense” can only be invoked in cases involving an intruder. When two people are lawfully present inside a dwelling, one of the occupants cannot use the castle doctrine as justification for using force against another person who is lawfully present. Furthermore, the doctrine only applies inside the home itself. It does not apply to the areas surrounding the home such as the driveway, porch, so-called “common areas,” the sidewalk, or lawn.