Supreme Court’s Ghost Guns Ruling: Dealers, Builders, State Laws

In Bondi v. VanDerStok, decided March 26, 2025, the Supreme Court’s ghost guns ruling upheld the ATF’s 2022 regulation by a 7–2 vote, confirming that federal law lets the agency treat ghost gun kits and unfinished frames or receivers as firearms. That means those products must carry serial numbers, and dealers must run background checks before selling them.¹

What the Court Decided

Justice Neil Gorsuch wrote for the majority, joined by Chief Justice Roberts and Justices Sotomayor, Kagan, Kavanaugh, Barrett, and Jackson. The Court held that the ATF’s rule “is not facially inconsistent with” the Gun Control Act of 1968.¹

The reasoning came in two parts. On weapon parts kits, the majority said the word “weapon” in the statute can describe an unfinished object when the intended function is obvious. A kit sold with every component needed to build a semiautomatic pistol, marketed for that purpose, qualifies as a weapon before assembly. The Court compared these kits to starter guns, which fire blanks but can be cheaply modified to shoot live rounds and have long been treated as firearms under the statute’s “readily converted” language. A Polymer80 kit that assembles into a working pistol in about 20 minutes with common tools meets the same standard.¹

On unfinished frames and receivers, the Court called these terms “artifact nouns,” meaning words that can describe incomplete objects when the intended finished product is clear. A partially milled receiver needing only minutes of standard work to function falls within the statute.¹

Justices Thomas and Alito dissented. Thomas focused on the statutory text, arguing that Congress used “readily converted” language for weapons but deliberately left it out of the provision covering frames and receivers. Under his reading, a partially complete frame is no more a “frame or receiver” than flour and eggs are a cake.¹

Why the Rule Existed in the First Place

Ghost guns are firearms assembled from kits or parts, built at home, and sold without the serial numbers stamped on commercially manufactured weapons. Because they carry no identifying marks, law enforcement cannot trace them when they turn up at crime scenes. The Court’s opinion noted the scale: in 2017, roughly 1,600 ghost guns were submitted to the federal government for tracing. By 2021, that number had passed 19,000.¹

Federal firearms regulation begins with 18 U.S.C. § 921(a)(3), which defines a “firearm” to include any weapon that fires a projectile using an explosive, any weapon designed to do so, any weapon that can readily be converted to do so, and the frame or receiver of such a weapon.² For decades, the frame or receiver was the only individual part treated as a regulated firearm. Manufacturers exploited that by selling frames advertised as “80 percent” finished, arguing the products hadn’t crossed the line into being a regulated component.

In April 2022, the ATF finalized a rule treating partially complete frames or receivers as regulated firearms when they can quickly and easily be made functional, and bringing weapon parts kits under the definition when the kit is designed to be readily assembled into a working gun.³ The rule excludes raw stock like blocks of metal or liquid polymers that haven’t been shaped toward becoming a frame or receiver.

What Changes for Dealers and Manufacturers

With the rule now confirmed, anyone selling, manufacturing, or dealing in weapon parts kits or unfinished frames and receivers that can be readily completed into functional firearms must comply with several requirements:

Products must be stamped with serial numbers.
Sales through licensed dealers require federal background checks on purchasers.
Detailed sales records must be maintained.
Transaction records must be retained indefinitely rather than for the old 20-year period.⁴

Licensed dealers who receive a privately made firearm, for example as a trade-in, must mark it with a serial number within seven days or before reselling it, whichever comes first.⁵

Justice Kavanaugh’s concurrence addressed a fair-notice question that matters here. The Gun Control Act penalizes licensing, recordkeeping, and serialization violations only when the person acted “willfully,” meaning they knew their conduct was unlawful. Background check violations carry a lower “knowingly” standard, which requires awareness of the facts but not necessarily of the law.¹ Manufacturers uncertain whether a specific product is covered can request a formal ATF classification to resolve the question before selling it.

If You Build a Firearm for Personal Use

Federal law still does not require you to add a serial number or register a firearm you build purely for your own use rather than for sale.⁵ The Bondi decision did not change that.

What did change is upstream. If you buy a kit or an unfinished frame that the ATF now treats as a firearm, the seller must run a background check and the product itself must carry a serial number when you receive it.

If you later decide to sell or transfer a home-built gun and bring it to a licensed dealer to handle the transaction, the dealer must engrave a serial number on it within seven days or before the sale, whichever comes first.⁴ Gunsmith fees for serialization engraving typically run between $65 and $130.

What the Ruling Left Open

The Court decided this as a facial challenge, meaning the question was whether the ATF’s rule is invalid in all circumstances. Ruling that it isn’t leaves room for later disputes over specific products. Future as-applied challenges can still argue that a particular unfinished frame sits too far from completion to qualify as a firearm under the statute. Where the line falls between a regulated component and raw material will continue to be worked out product by product.

State Laws Can Go Further

Roughly 16 states have enacted their own ghost gun regulations, and many go beyond the federal rule. Some require serial numbers on all privately made firearms, including those built for personal use. Others ban the sale or possession of unserialized weapons entirely, with criminal penalties that can include imprisonment. The federal rule sets a floor. If you own or plan to build a firearm from a kit, check your state’s law along with the federal requirements.

3D-Printed Firearms

Ghost guns made with 3D printers raise a separate federal concern beyond serialization. The Undetectable Firearms Act, 18 U.S.C. § 922(p), makes it a federal crime to manufacture, possess, sell, or transfer any firearm that cannot be detected by a walk-through metal detector or that does not produce an accurate image under an airport X-ray machine.⁶ A firearm printed entirely from plastic can violate this law unless it contains enough metal to trigger detection equipment.

Federal law does not ban 3D-printed firearms outright. You can legally print a frame or receiver for personal use as long as the finished product meets the detectability requirement and complies with the broader Gun Control Act framework.⁵ If you intend to sell or distribute 3D-printed firearms, the ATF’s serialization and licensing rules apply the same way they do to any other manufacturer. The Bondi decision confirmed that the ATF’s expanded definitions cover partially complete frames regardless of how they were made.

1
Supreme Court of the United States. Bondi v. VanDerStok, No. 23-852
2
Office of the Law Revision Counsel. 18 USC 921 – Definitions
3
Bureau of Alcohol, Tobacco, Firearms and Explosives. Summary of Final Rule 2021R-05F
4
Congressional Research Service. Supreme Court Upholds ATF Ghost Gun Regulation in Bondi v. VanDerStok
5
Bureau of Alcohol, Tobacco, Firearms and Explosives. Privately Made Firearms
6
Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts