"A lot of people have been moseying around this issue, but if you can't arm your own Cessna, you probably can't arm your own drone," Singer tells U.S. News. "We're in the early days of this, so anyone saying this could never ever happen is a pretty good way to prove they don't know what they're talking about."
The Second Amendment question was recently explored in-depth by Dan Terzian, a U.S. District Court clerk in Guam, who published "The Right to Bear (Robotic) Arms" in the Penn State Law Review earlier this year.
According to Terzian, the answer to that question comes down to the interpretation of the Supreme Court in a couple cases, most importantly District of Columbia v. Heller, the 2008 decision that overturned Washington's handgun ban.
That decision held that the Second Amendment "protects an individual right to possess a firearm unconnected with service in the militia, and to use that arm for traditionally lawful purposes, such as self-defense within the home," but limits the amendment's protections to weapons that are "in common use at the time."
By that definition, robotic weapons would almost certainly not be considered in "common use," much like rocket launchers, tanks and cannons. But Terzian says that as the technology improves, armed drones could one day become popular enough to become commonplace.
"There are a lot of people in other countries who are basically making autonomous weapons at their home, but they're not necessarily using handguns, they're using Nerf guns or paintball guns," Terzian says. "There's no fundamental [Second Amendment] difference between using a squirt gun and a firearm."
According to Terzian, Congress could, with one law, make it illegal for Rand Paul's nightmare to come true - at least if perpetrated by a civilian. Because armed drones are currently not common, Congress could simply expressly ban them, making it impossible for them to ever become an everyday thing.
"If Congress chose, it could ban robotic weapons, meaning robots would never be in common use, and thus never armed," he writes. "But just because Congress can ban them, does not mean it should ... robotic weapons [could be] both more effective and safer than firearms, so banning them, as opposed to regulating them, would by myopic."
Lawmakers in Washington have proposed bills that would restrict when private companies, individuals and public agencies can use unarmed drones, but it has yet to strongly consider armed drone legislation.
If Congress doesn't act, Terzian argues that one day, robotic weapons could defend factories, public places and, eventually, people's homes. As autonomous decision-making intelligence improves, Terzian says that automated weapons might have legitimate self-defense uses that could potentially be lawful.
It's also unclear, he says, whether someone would have the right to attach their handgun to a small drone and then use it for target practice on their private property. The FAA certainly wouldn't approve, but Terzian says it might not be inherently illegal.
"If they're using a pistol attached to a mechanical device - you have a right to that pistol, you can do whatever you want with it unless you are breaking the law with it," he says. "I think it's at least possible that some of those laws could be challenged. I'm not sure we're to the point where you'd win, but you could try."