Massachusetts may be one of the most liberal states in the country, but its citizens are still permitted to defend themselves from attack.
The self-defense laws are best summarized by Jury Instructions 9.260 which are read to jurors whenever a self-defense claim is made during trial.
All quotes in this post will be from those instructions.
Self-Defense: Non-Deadly Force
To legally use force in self-defense you must “reasonably believe [you are] being attacked or immediately about to be attacked” and that your “safety [is] in immediate danger.”
You must also “do everything reasonable in the circumstances to avoid physical combat before resorting to force.”
Finally, you may not use more force “than [is] reasonably necessary in the circumstances.”
Self-Defense: Deadly Force
Deadly force is defined as any “force intended or likely to cause death or great bodily harm.”
To use such force in self-defense you must “reasonably and actually believe that [you are] in immediate danger of great bodily harm or death.”
Again you must “do everything reasonable in the circumstances to avoid physical combat before resorting to force” and not use more force “than [is] reasonably necessary in the circumstances.”
The “Castle Rule”
You are generally not required to retreat from your home if threatened by an intruder.
According to the rules, “[a] person lawfully occupying a house, apartment or other dwelling is not required to retreat from or use other means to avoid combat with an unlawful intruder.”
However, you must reasonably believe “that the intruder is about to inflict great bodily injury or death on [you] or on another person lawfully in the dwelling” and use “only reasonable means to defend [yourself] or the other person.”
Defense of Property
You may use “reasonable force, but not deadly force, to defend [your] lawful property against someone who has no right to it.”
Likewise, you may use “reasonable force, but not deadly force, to regain lawful possession of [your] property where [your] possession has been momentarily interrupted by someone with no right to the property.”
Finally, you can use reasonable but not deadly force “to remove a trespasser from [your] property after the trespasser has been requested to leave and has refused to do so.”
The laws regarding self-defense are extensive and, in many ways, subjective. What one juror considers reasonable force another may view as excessive violence.
If you have additional questions regarding the laws of self-defense, begin by reading the cited jury instructions in their entirety. Then review the dozens of cases cited at the end of the document.
And always feel free to contact me via email at firstname.lastname@example.org.