Massachusetts' ban on the private possession of stun guns—an "electrical weapon" under the statute—does not violate the Second Amendment right to bear arms, the state's top court has ruled.

The decision says (PDF) that the US Constitution's framers never envisioned the modern stun-gun device, first patented in 1972. The top court said stun guns are not suitable for military use, and that it did not matter whether state lawmakers have approved the possession of handguns outside the home.

Nevertheless, we note that stun guns deliver a charge of up to 50,000 volts. They are designed to incapacitate a target by causing disabling pain, uncontrolled muscular contractions, and general disruption of the central nervous system.... It is difficult to detect clear signs of use and misuse of stun guns, unlike handguns. Stun guns can deliver repeated or prolonged shocks without leaving marks. ...The Legislature rationally could ban their use in the interest of public health, safety, or welfare. Removing from public access devices that can incapacitate, injure, or kill a person by disrupting the central nervous system with minimal detection is a classic legislative basis supporting rationality. It is immaterial that the Legislature has not banned weapons that are more lethal. Mathematical precision by the Legislature is not constitutionally required.

The court, ruling in the case of a Massachusetts woman caught with stun gun, said the stun gun is a "thoroughly modern invention" not protected by the Second Amendment, although handguns are protected.

Moreover, although modern handguns were not in common use at the time of enactment of the Second Amendment, their basic function has not changed: many are readily adaptable to military use in the same way that their predecessors were used prior to the enactment. A stun gun, by contrast, is a thoroughly modern invention. Even were we to view stun guns through a contemporary lens for purposes of our analysis, there is nothing in the record to suggest that they are readily adaptable to use in the military. Indeed, the record indicates "they are ineffective for . . . hunting or target shooting." Because the stun gun that the defendant possessed is both dangerous per se at common law and unusual, but was not in common use at the time of the enactment of the Second Amendment, we conclude that stun guns fall outside the protection of the Second Amendment.

The decision, the most recent analysis of the Second Amendment by any top court, comes as all types of and manner of weapons are being constructed at home via 3D printing technology. The latest showdown about those weapons surfaced last month, when FedEx refused to ship a box that makes homemade metal semi-automatic rifles.

The Massachusetts case, decided last week, concerned Jaime Caetano, who lives in one of five states making it illegal for private citizens to posses stun guns. She appealed her 2013 conviction, on Second Amendment and self-defense grounds, claiming she had a right to the weapon to protect herself from what she said was an abusive father of her children. The penalty for breaching the law carries up to a 2.5-year maximum jail term. She was caught with the device outside a grocery store after allowing the authorities, who were looking for a shoplifter, to search her purse.

The law in question, the court said, forbids the private possession of a "portable device or weapon from which an electrical current, impulse, wave or beam may be directed, which current, impulse, wave or beam is designed to incapacitate temporarily, injure or kill" except by specified public officers or suppliers of such devices, if possession is "necessary to the supply or sale of the device or weapon" to agencies utilizing it.

In 2008, the US Supreme Court, in a decision known as Heller (PDF), overturned a District of Columbia statute and ruled that a ban on handgun possession in the home violates the Second Amendment, as does its prohibition against rendering any lawful firearm in the home operable for the purpose of immediate self-defense." Now, every state allows people to carry weapons of sorts, some with or without permits.

The Massachusetts top court concluded that the woman could have applied for a permit to carry a concealed weapon, like a handgun instead.

"Barring any cause for disqualification the defendant could have applied for a license to carry a firearm," the court ruled.

The court added that, "possession of mace or pepper spray for self-defense no longer requires a license."

That seems strange, according to Michael E. Rosman, general counsel for the Center for Individual Rights in Washington, D.C.

In Massachusetts, he told the Boston Globe, the public is "permitted with a license to have guns and carry guns. It makes no sense to say you shouldn’t be allowed to have a weapon that you can defend yourself with, but is less dangerous to the attacker."

The ban on stun guns, he told the Globe, is “perverse” because they are less lethal than other weapons.

The public, he said, is “being pushed into handgun possession by the ban on stun guns.”