WASHINGTON >> A majority of the Supreme Court appeared sympathetic Tuesday to the Biden administration’s restrictions on kits to make homemade guns that skirt background checks and serial numbers.

At least five justices seemed to favor the measures, with at least two conservatives, Chief Justice John Roberts and Justice Amy Coney Barrett, showing skepticism toward the plaintiffs, gun manufacturers and owners who argued that the administration had overstepped its bounds in regulating so-called ghost guns.

The rule, part of a broader effort by President Joe Biden to address gun violence, sought to curtail the soaring popularity of the guns, weapons made from kits available for purchase online and heralded as easy enough to assemble in less than an hour.

The rule in question

Under the regulation, enacted in 2022 by the Bureau of Alcohol, Tobacco, Firearms and Explosives, gun makers and sellers must be licensed to sell the kits, the products must be marked with serial numbers so they can be traced, and would-be buyers must pass a background check.

Should the limits be upheld, the ruling would be a departure for a court that has often proved unreceptive to the power of administrative agencies or gun restrictions more broadly. Last term, it overturned a Trump-era ban on bump stocks, firearm attachments that enable semiautomatic weapons to fire at nearly the rate of a machine gun.

Over nearly an hour and a half of arguments, the justices raised a series of analogies to get at the heart of the case. Do ghost gun kits that can be quickly and easily assembled fall under the definition of firearms in the Gun Control Act of 1968? And can a gun that is only partly complete also be regulated under that law?

In urging the justices to uphold the measure, Solicitor General Elizabeth Prelogar described “an explosion in crimes committed with ghost guns,” saying that the kits appealed to criminals because they were difficult to trace and did not require background checks.

“The reason why you want a ghost gun is specifically because it’s unserialized and can’t be traced,” Prelogar said.

Varied analogies: cars, omelets

When Peter Patterson, the lawyer for the gun groups, argued that gun enthusiasts might enjoy building firearms from the kits, Roberts, who until then had been largely silent, questioned whether the kits were really aimed at hobbyists. He drew an analogy to people who love tinkering with cars.

“Drilling a hole or two,” Roberts said, “doesn’t give the same sort of reward that you get as working on your car on the weekends.”

Patterson responded by pointing to a reporter in California who had ordered a gun kit to assemble. That reporter had to enlist friends to help, Patterson said. (The news article Patterson appeared to refer to described the process of buying and building a ghost gun as “shockingly easy.”)

The chief justice pushed back on Patterson’s response.

“I don’t know the skills of the particular reporter,” Roberts replied, to laughter.

The justices appeared eager to draw comparisons to everyday hobbies and situations. Omelets played a starring role.

Justice Samuel Alito pressed Prelogar about when parts of something, put together, made something new — as in, when do gun kit parts become a gun?

“If I show you — I put out on a counter some eggs, some chopped-up ham, some chopped-up pepper and onions, is that a Western omelet?” Alito asked.

Prelogar said no. The difference, she said, is that the group of random ingredients could be used to make things other than an omelet.

Barrett, who has emerged near the court’s ideological middle in recent terms, chimed in.

“Would your answer change if you ordered it from HelloFresh, and you got a kit, and it was like turkey chili, but all of the ingredients are in the kit?”

Yes, Prelogar replied.

She added that Barrett had captured “the more apt analogy here” because ghost gun kits are not a random assortment of parts but rather a group of components sold together for a specific purpose.

Sellers’ intentions

Justice Brett Kavanaugh then raised a concern that sellers with good intentions could be swept up in government regulation meant for criminals.

“So what about the seller, for example, who is truly not aware, truly not aware that they are violating the law and gets criminally charged?” he asked.

The federal agency “is not trying to hide the ball here,” Prelogar said. “The point of the agency is not a game of gotcha to try to criminally prosecute people.”

Prelogar said that the regulation governed commercial sales and that the gun kits came with essentially everything needed to quickly build a gun. The only tools required for ghost gun kits were simple, everyday instruments, like a tool for filing the nails of a pet dog.

The regulation, she noted, was aimed at stopping criminals, not hobbyists or well-intentioned manufacturers and sellers.

“What the evidence shows is that these guns were being purchased and used in crime,” Prelogar said near the close of arguments. “They were sold to be crime guns.”

Although it centered on guns, the case before the court was not about the Second Amendment, but rather about the limits of the power of administrative agencies.

The dispute is the latest challenge to the federal government’s limited attempts to address gun violence, particularly as legislative efforts have stalled in Congress.

Previous rulings

The Biden administration asked the Supreme Court to intervene after lower courts blocked the regulation.

In 2023, Judge Reed O’Connor of U.S. District Court in the Northern District of Texas, who was appointed by President George W. Bush, agreed that the administration had overstepped. “Even if it is true that such an interpretation creates loopholes that as a policy matter should be avoided, it is not the role of the judiciary to correct them,” he wrote. “That is up to Congress.”

Three judges from the 5th U.S. Circuit Court of Appeals — all of them appointed by President Donald Trump — upheld that ruling.

The case has reached the justices before, on an emergency basis.

The court, by a 5-4 vote, with Roberts and Barrett joining its liberal wing, sided with the Biden administration, reinstating the regulations temporarily as the legal challenge continued.