The case, VanDerStok v. Garland, centers on the legality of a 2022 rule from the Bureau of Alcohol, Tobacco, Firearms, and Explosives that treats “readily convertible” ghost gun kits like regular firearms, subjecting them to serial number requirements and background checks. Ghost guns, which are untraceable and can be easily assembled from kits sold online, have been increasingly recovered from crime scenes, according to federal data.

Responding to an explosion in ghost gun use, the ATF clarified in a 2022 rule known as the “Frame and Receiver” rule that gun regulations requiring serial numbers and background checks apply to these “readily convertible” kits, too, relying on the Gun Control Act of 1968.

During Tuesday’s oral arguments, a majority of justices seemed inclined to support the ATF’s position.

“If there is a market for these kits for hobbyists, they can be sold to hobbyists,” Solicitor General Elizabeth Prelogar said, dismissing concerns that self-assembly gun kits would not be available for purchase under the ATF rule.

“You just have to comply with the requirements of the Gun Control Act. Someone who is lawfully allowed to possess a firearm and wants to build it can purchase that kit if they undergo a background check. And so if there is a market for these products, they can operate under the statute,” Prelogar added.

From ghost guns to omelets to turkey chili

Republican-appointed Justice Samuel Alito posed several questions that brought him out as perhaps the jurist most skeptical of the idea that a collection of unassembled parts can be considered a gun, so much so that he turned to a discussion about food.

“Here’s a blank pad, and here’s a pen, all right? Is this a grocery list?” Alito asked, holding up a pad in the courtroom. “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?”

Prelogar pushed back on Alito’s breakfast analogy but said Republican-appointed Justice Amy Coney Barrett was more spot-on with her turkey chili comparison.

“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?” Barrett said, referring to the food kit delivery service.

Overall, there appeared to be a majority of justices leaning toward the government’s argument, particularly on the issue of the “readily convertible” standard, language in the statute that has been consistently applied for decades.

The challengers, led by gun owners and manufacturers, argued that the ATF’s rule violates the Gun Control Act of 1968, which they contend applies only to fully assembled firearms. They proposed an alternative test, which focuses on the critical machining of gun parts, but this idea was met with skepticism from several justices, including the high court’s Democratic-appointed members.

At one point, Justice Sonia Sotomayor suggested that the Supreme Court often takes on cases when a federal agency is “just taking over what is really Congress’s business,” asking Prelogar if “that is a storyline that the respondents here can tell about this regulation?”

“No, I don’t think there is any terrible way to characterize this regulation as an attempt to change the meaning of the statute to confront a new problem,” Prelogar said.

The case arrives at a critical time for the 6-3 Republican appointed-majority Supreme Court, which has bolstered Second Amendment freedoms in recent years, as seen in New York State Rifle & Pistol Association v. Bruen, as well as Cargill v. Garland, a case from the last term that saw the justices side against the ATF bump stocks ban.

However, the tone of the oral arguments this week suggested that the justices may defer to the ATF’s interpretation of the statute in this instance, particularly given the public safety concerns raised by the rise of ghost guns.

The eventual ruling could have significant implications for future firearm regulations and the limits of federal agency authority. A decision is expected by the end of the term in June.