Originally published November 28, 2014 at 6:04 PM | Page modified November 28, 2014 at 6:56 PM

BOSTON Jaime Caetano was beaten so seriously by her former boyfriend that she ended up in the hospital. So when a friend offered her a stun gun to protect herself, she took it.

Caetano, who is homeless, never had to use it but she now finds herself at the center of a Second Amendment case headed to the highest court in Massachusetts.

The Supreme Judicial Court is being asked to decide whether a state law that prohibits private citizens from possessing stun guns infringes on their right to keep and bear arms. In an unusual twist, the court is also being asked to examine whether the Second Amendment right to defend yourself in your own home applies in the case of a homeless person.

Arguments before the court are scheduled Tuesday.

Police found Caetanos stun gun in her purse during a shoplifting investigation at a supermarket in 2011. She told police she needed it to defend herself against her ex-boyfriend, against whom she had obtained multiple restraining orders.

During her trial, Caetano, 32, testified that her ex-boyfriend repeatedly came to her workplace and threatened her. One night, she showed him the stun gun and he got scared and left me alone, she said.

She was found guilty of violating the state law that bans private possession of stun guns, devices that deliver an electric shock when pressed against an attacker.

In her appeal, her lawyer, Benjamin Keehn, argues that a stun gun falls within the meaning of arms under the Second Amendment. Keehn wrote in a legal brief that the states ban cannot be squared with the fundamental right to keep and bear arms. He also argues that self-defense outside the home is part of the core right provided by the Second Amendment.

Massachusetts is one of five states that ban stun guns and Tasers for private citizens, said Eugene Volokh, a constitutional-law professor at UCLA who has written extensively about Second Amendment issues. The devices are used by law-enforcement agencies around the country.

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Homeless womans stun gun a right-to-bear-arms case