## Facts

- Massachusetts banned possession of stun guns through Mass. Gen. Laws ch. 140, § 131J.
- Jaime Caetano, after repeated threats and assaults by an abusive ex-boyfriend and ineffective restraining orders, obtained a stun gun from a friend for self-defense.
- When confronted and threatened outside her workplace, Caetano displayed the stun gun and avoided an assault.
- During an unrelated police investigation, officers searched Caetano’s bag with her consent, found the stun gun, and arrested her.
- At a bench trial, it was undisputed that she possessed the stun gun, it was covered by § 131J, and she possessed it for self-defense.
- Evidence indicated stun guns were widely purchased for self-defense and were lawful in many states, though handguns were more common.
- The trial court rejected her Second Amendment defense and convicted her; the Massachusetts Supreme Judicial Court affirmed on the ground that stun guns were not protected “arms.”

## Issues

1. Whether the Second Amendment protects possession of a stun gun for self-defense.
2. Whether a state court may deny Second Amendment coverage to stun guns because they were not in common use at the founding, are “unusual” because modern, or lack military utility.

## Decision

- The U.S. Supreme Court unanimously vacated the Massachusetts Supreme Judicial Court’s judgment and remanded.
- The Court held the state court’s reasons for excluding stun guns from Second Amendment protection conflicted with District of Columbia v. Heller and McDonald v. Chicago.
- The Court rejected three rationales: (1) excluding weapons not common in 1791, (2) treating “unusual” as meaning modern, and (3) limiting protection to weapons suitable for military use.
- Justice Alito, joined by Justice Thomas, concurred in the judgment, emphasizing the self-defense context and arguing the ban burdened a class of arms commonly used for lawful purposes.

## Legal Principles

- The Second Amendment extends, at least presumptively, to all “bearable arms,” including weapons not in existence at the founding.
- The Second Amendment right applies to the states.
- A weapon is not outside Second Amendment coverage merely because it is modern or was not common at the time of ratification.
- Courts may not deny coverage on the ground that a weapon lacks military utility, because the right is not limited to arms useful in warfare.
- When evaluating a weapon ban, lower courts must apply Heller’s framework and may not rely on rationales that contradict it.

## Conclusion

The Supreme Court did not finally decide the constitutionality of Massachusetts’s stun-gun ban, but vacated and remanded because the state court’s exclusion of stun guns from Second Amendment protection rested on reasoning rejected by controlling precedent.


Caetano v. Massachusetts, 136 S. Ct. 1027 (2016)