After a “bad altercation” with an abusive boyfriend put her in the hospital, Jaime Caetano found herself homeless and “in fear for [her] life.” She obtained multiple restraining orders against her abuser, but they proved futile. So when a friend offered her a stun gun “for self-defense against [her] former boy friend,” Caetano accepted the weapon.

It is a good thing she did. One night after leaving work, Caetano found her ex-boyfriend “waiting for [her] outside.” He “started screaming” that she was “not gonna [expletive deleted] work at this place” any more because she “should be home with the kids” they had together. Caetano’s abuser towered over her by nearly a foot and outweighed her by close to 100 pounds. But she didn’t need physical strength to protect herself. She stood her ground, displayed the stun gun, and announced: “I’m not gonna take this anymore…. I don’t wanna have to [use the stun gun on] you, but if you don’t leave me alone, I’m gonna have to.” The gambit worked. The ex-boyfriend “got scared and he left [her] alone.”

It is settled that the Second Amendment protects an individual right to keep and bear arms that applies against both the Federal Government and the States. That right vindicates the “basic right” of “individual self-defense.” Caetano’s encounter with her violent ex-boyfriend illustrates the connection between those fundamental rights: By arming herself, Caetano was able to protect against a physical threat that restraining orders had proved useless to prevent. And, commendably, she did so by using a weapon that posed little, if any, danger of permanently harming either herself or the father of her children….

The Supreme Judicial Court suggested that Caetano could have simply gotten a firearm to defend herself. But … a weapon is an effective means of self-defense only if one is prepared to use it, and it is presumptuous to tell Caetano she should have been ready to shoot the father of her two young children if she wanted to protect herself. Courts should not be in the business of demanding that citizens use more force for self-defense than they are comfortable wielding.

Countless people may have reservations about using deadly force, whether for moral, religious, or emotional reasons — or simply out of fear of killing the wrong person. I am not prepared to say that a State may force an individual to choose between exercising that right and following her conscience, at least where both can be accommodated by a weapon already in widespread use across the Nation….

A State’s most basic responsibility is to keep its people safe. The Commonwealth of Massachusetts was either unable or unwilling to do what was necessary to protect Jaime Caetano, so she was forced to protect herself. To make matters worse, the Commonwealth chose to deploy its prosecutorial resources to prosecute and convict her of a criminal offense for arming herself with a nonlethal weapon that may well have saved her life. The Supreme Judicial Court then affirmed her conviction on the flimsiest of grounds….

If the fundamental right of self-defense does not protect Caetano, then the safety of all Americans is left to the mercy of state authorities who may be more concerned about disarming the people than about keeping them safe.