OAKLAND (CBS SF) — California Attorney General Rob Bonta on Thursday voiced his support of a proposed rule change by the ATF that would clarify the agency’s definition of what qualifies as a firearm to include ghost-gun kits.

In a comment letter to the Bureau of Alcohol, Tobacco, Firearms, and Explosives, Bonta lauded the agency for its reversal of a prior determination that so-called “80 percent” frames and receivers — which are commonly used to assemble untraceable ghost guns — are not firearms under the Gun Control Act (GCA).

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In 2020, the California Department of Justice (DOJ) and Giffords Law Center to Prevent Gun Violence led a coalition that filed a lawsuit demanding the ATF change its interpretation of the GCA and classify these frames and receivers as firearms, making them subject to federal firearm statutes and regulations.

“We applaud the Biden Administration for taking steps to enforce commonsense gun regulation at the federal level. Right now, do-it-yourself ghost gun kits allow anyone with a credit card and an internet connection to purchase and build a fully operable, untraceable weapon in minutes with little to no restriction,” the Attorney General said in a press release. “The ATF’s Proposed Rule will bring federal law up to speed with California law, and make it clear that unfinished frames and receivers are firearms, and will be regulated as such.”

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The ATF’s previous interpretation of the GCA has led to the proliferation of ghost guns in California and throughout the country. According to the ATF, as of 2019, 30% of all firearms recovered in California were not serialized.

Additionally, Giffords Law Center to Prevent Gun Violence found that in Los Angeles from 2015 to 2019, the number of ghost guns recovered increased by 144%. Alarmingly, in San Francisco, while no ghost guns were recovered in 2015, ghost gun recoveries increased by 1,517% between 2016 to 2019.

The announcement comes the day after San Francisco District Attorney Chesa Boudin said his office is suing three businesses that manufacture and distribute ghost guns throughout the state.

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The civil lawsuit was filed against Blackhawk Manufacturing Group, Inc.; GS Performance, LLC; MDX Corporation; and additional unknown defendants to stop the spread of the untraceable weapons.