Washington DC - The Supreme Court appeared poised on Tuesday to uphold federal regulation of "ghost guns" – firearms sold in easy-to-assemble kits.

Gun manufacturers and gun rights groups are challenging a 2022 rule from the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) that requires ghost guns, like other firearms, to have serial numbers and their purchasers to undergo background checks.

The ATF rule also requires commercial sellers of what are known as "buy-build-shoot" kits to be licensed and maintain records.

"Those basic requirements are crucial to solving gun crimes and keeping guns out of the hands of minors, felons, and domestic abusers," Solicitor General Elizabeth Prelogar argued before the Supreme Court on Tuesday.

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"But in recent years, companies like the respondents here have tried to circumvent those requirements," Prelogar said. "They've begun selling firearms as easy-to-assemble kits... that require minimal work to be made functional."

"Those untraceable guns are attractive to people who can't lawfully purchase them or who plan to use them in crimes," Prelogar said. "As a result, our nation has seen an explosion in crimes committed with ghost guns."

Ghost guns were being marketed as "ridiculously easy to assemble," she said, with manufacturers boasting that "you can go from opening the mail to having a fully functional gun in as little as 15 minutes, no serial number, background check or records required."

Prelogar said she had put one of the kits together herself and – despite being "someone who struggles with IKEA furniture" – she found it quite easy, involving only a couple of steps, including drilling a few holes.

Peter Patterson, representing the gun manufacturers and gun rights groups objecting to the ATF rule, argued that the federal agency had exceeded its authority.

"ATF has expanded the definition of firearm to include collections of parts that are not weapons," Patterson said, and a kit should not be considered a firearm under the Gun Control Act passed by Congress in 1968.

Patterson said the kits were popular among gun hobbyists, "like individuals who enjoy working on their car every weekend."

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That drew a wry response from Chief Justice John Roberts, one of several conservative justices on the bench who appeared skeptical of the challenge to the ATF rule.

"Drilling a hole or two, I would think, doesn't give the same sort of reward that you get from working on your car on the weekends," Roberts said.

According to ATF figures, nearly 20,000 ghost guns were recovered at crime scenes in the US in 2021 – a tenfold increase from 2016. Prelogar said the number has dropped dramatically since the 2022 rule went into force.

The Biden administration appealed to the Supreme Court after a district court struck down the ATF rule, and its ruling was upheld by a conservative-dominated appeals court panel.

The Supreme Court, by a 5-4 vote, stayed the order of the lower courts striking down the ATF rule and decided to hear the case. It is expected to deliver a decision before the end of June 2025.