The Supreme Court will hear oral argument next week in a challenge to a 2022 federal rule that seeks to regulate “ghost guns” – firearms without serial numbers that, the Bureau of Alcohol, Tobacco, Firearms, and Explosives says, almost anyone can quickly assemble with parts that they purchase, often in a kit online or through the mail. Serial numbers are used by law enforcement to track guns used in crime.

Defending the rule, the ATF argues that it is necessary to address an “urgent public safety and law enforcement crisis” created by the “exponential” increase in ghost guns. And the agency stresses that the rule does not seek to ban ghost guns, but instead simply tries to ensure that they are regulated in the same way as other commercial gun sales.

But the gun owners and gun manufacturers challenging the rule counter that the federal government has not previously required a license to build a gun for private use. And they push back against the ATF’s efforts to portray ghost guns as a problem. Even without the 2022 rule, they say, federal laws regulating guns still apply to “the vast majority of firearms produced in this country,” and, they claim, the ATF’s own data shows that ghost guns are “not a substantial source of firearms for criminals.”

Background

The Gun Control Act of 1968 requires gun manufacturers and dealers to obtain a federal license, keep records of gun sales and transfers, and conduct background checks. Manufacturers must also put a serial number on guns. The law defines a “firearm” as “any weapon … which will or is designed to or may readily be converted to expel a projectile by the action of an explosive,” including “the frame or receiver of any such weapon.”

Unserialized, homemade guns have become increasingly popular. Law enforcement saw a 10-fold increase in the number of ghost guns reported to the ATF from 2016 to 2022, according to data from the Biden administration.

Ghost gun kits can be bought online without presenting identification or undergoing the background check required by federally licensed dealers. They can also be purchased anonymously with cryptocurrency or, as regulators note, a pre-paid debit card from a convenience store. Background checks in commercial gun sales are used to prevent felons, domestic abusers, and children from buying guns. In a separate ruling in June, the Supreme Court affirmed that the Constitution allows the government to prohibit individuals who are subject to domestic violence restraining orders from owning or carrying a gun.

The ATF issued the 2022 rule to make clear that the requirements imposed by federal law on gun dealers and manufacturers also apply to the sale and manufacture of ghost guns. The rule defines “firearm” to include products, such as weapon parts kits, that can be converted into an operational gun or a functional frame (the basic structure of the gun) or receiver (the part of the gun that houses, among other things, the firing mechanism). The rule also clarified that the terms “frame” and “receiver” include partially complete or disassembled frames or receivers that can be “readily” completed or converted to function as a frame or receiver.

In August 2022, a group of challengers that included two individual gun owners and a gun-rights advocacy organization went to federal court in Fort Worth, Tex., seeking to block the rule from going into effect. They were later joined by several manufacturers and another advocacy group. The challengers contested the provisions of the 2022 rule that included weapon parts kits within the 1968 law’s definition of “firearm” and included partially complete frames or receivers within the law’s coverage.

In June 2023, U.S. District Judge Reed O’Connor agreed with the challengers and barred the ATF from enforcing the rule anywhere in the United States.

But later that summer, the Supreme Court granted the Biden administration’s request to be able to enforce the rule while it appealed. The vote was 5-4, with Justices Clarence Thomas, Samuel Alito, Neil Gorsuch, and Brett Kavanaugh indicating that they would have turned down the government’s request and allowed O’Connor’s order to remain in place.

When the U.S. Court of Appeals for the 5th Circuit eventually heard the ATF’s appeal, it largely upheld O’Connor’s decision. That prompted the Biden administration to come to the Supreme Court earlier this year, asking the justices to decide whether ghost gun parts and kits are “firearms” regulated by the 1968 act.

Arguments

The ATF and the challengers disagree on virtually every element of the case before the Supreme Court, starting with the ATF’s premise – that almost anyone can quickly assemble a ghost gun using only “basic tools and rudimentary skills” “in as little as twenty minutes.”

Both the challengers and a “friend of the court” brief filed by a former ATF official contend that the process is significantly harder than the ATF suggests. Putting a ghost gun together can require considerable time, specialized tools and technical expertise, they say, and the out-of-pocket costs can add up to more than the expense of buying a new, ready-made gun.

A central issue before the justices is whether the 1968 law gives the ATF the power to regulate ghost guns through the 2022 rule. The ATF insists that it does, arguing that the 1968 law does not apply only to guns that are already fully assembled. The rule “closely tracks” the text of the 1968 law, the ATF reasons, making clear that a weapon parts kit that may “readily be completed, assembled, restored, or otherwise converted to expel a projectile by the action of an explosive” is a “firearm.”

Similarly, the AFT observes, nothing in the 1968 law indicates that it applies only to frames and receivers that are complete and functional.

The ATF suggests that applying the 1968 law to ghost guns is really a matter of common sense. “If a State placed a tax on the sale of tables, chairs, couches, and bookshelves,” it explains, “IKEA could not avoid paying by insisting that it does not sell any of those items and instead sells ‘furniture parts kits’ that must be assembled by the purchaser.”

The challengers argue that the government’s comparison of weapons parts kits to IKEA bookshelves misses the mark. A better one, they write, “would be a box containing shelves and, instead of a frame to hold them, planks of wood that had been cut to length and drilled to do so.”

Both the history of efforts to regulate ghost guns and the text of the 1968 law itself, the challengers say, support invalidating the 2022 rule. Before ATF enacted the rule, the challengers note, Congress had considered, but did not pass, several proposals to amend the 1968 law to cover partially completed frames and receivers and parts kits – indicating that in Congress’s view the law as currently drafted does not cover them. And in other provisions of the act, Congress specifically included references to parts of weapons, demonstrating that it knows how to regulate weapons parts kits when it wants to.

Moreover, the 1968 law defines a “firearm” as a weapon that can “expel a projectile by the action of an explosive” and (among other things) weapons that is “designed” or “readily be converted” to do so. But although the law does not contain the same language for frames or receivers, the rule would interpret the act as if it did.

Such an interpretation, the challengers warn the justices, could have serious consequences: Because AR-15 receivers can usually be converted to function as machinegun receivers, sometimes quite easily, if “anything that can be ‘readily converted’ to function as a ‘frame or receiver’ is a ‘frame or receiver,’ then Americans who own AR-15 rifles, one of America’s ‘most popular firearms,’ run the risk of violating” the federal ban on unregistered machineguns. The 2022 rule, the challengers conclude, “thus risks turning law-abiding firearm owners into felons.”

The two sides also dispute whether the 2022 rule is consistent with the ATF’s past practice. The ATF insists that it is, telling the justices that for over a half-century it has “classified a product as a frame or receiver if it can readily be completed to function as a frame or receiver.”

But the challengers counter that if the ATF did have a practice of applying the definition outlined in the rule to partially complete frames and receivers, that practice would not be entitled to any deference because the agency never enshrined it in any regulations.

In any event, the challengers continue, regulations issued in the wake of the 1968 law to define frame or receiver “remained unchanged until 2022 and said nothing about precursors of frames or receivers or parts kits.”

If there is any remaining doubt about whether the rule goes beyond the ATF’s power, the challengers tell the justices, they should uphold the lower courts’ decisions invalidating the rule because it is “hopelessly vague.” For example, the challengers note, when it defines both “frame or receiver” and “weapons parts kits,” the 2022 rule relies on ATF’s definition of the term “readily,” which the agency bases on an eight-part list of considerations that “ATF appears to have made intentionally vague.”

The ATF rejects the contention that the 2022 rule contains the kind of “grievous ambiguity” required to rule in the challengers’ favor: “Dictionary definitions of the relevant terms, statutory context, ATF’s longstanding practice, precedent, and common sense all make clear that parts kits and partially complete frames and receivers that can readily be completed fall within the Act’s definition of ‘firearm.’”

Finally, the ATF urges the justices to look at the broader picture, stressing that allowing the lower courts’ decisions to stand would “recreate the same problem” that Congress was attempting to avoid when it enacted the 1968 law – keeping felons, juveniles, and others seeking guns for criminal purposes from evading regulation by acquiring guns by mail.

The challengers, however, reject the government’s suggestion that if the rule is struck down, people who should not have access to guns will be able to. By all accounts, they write, the partially completed frames and receivers and kits that the rule seeks to regulate “are favored by hobbyists, while the vast majority of criminals prefer to get firearms that have been professionally manufactured.” But if Congress wants to regulate ghost guns, they conclude, that decision is for it – and not ATF – to make.

This post is also published on SCOTUSblog.