In a landmark decision on March 26, 2025, the U.S. Supreme Court upheld federal regulations targeting "ghost guns," untraceable firearms assembled from kits or 3D-printed parts without serial numbers. The 7-2 ruling supports the Biden administration's efforts to regulate these firearms by mandating serial numbers, licenses, and background checks for gun kits and parts, aligning them with the 1968 Gun Control Act.

Ghost guns are privately made firearms lacking serial numbers, making them untraceable and appealing to individuals prohibited from purchasing firearms through traditional means. These weapons can be assembled from kits or created using 3D printers, often without background checks. Their proliferation has raised significant concerns among law enforcement agencies due to their increasing use in criminal activities. In 2021, local law enforcement agencies seized more than 19,000 ghost guns at crime scenes, a more than tenfold increase in just five years.

The Supreme Court's decision overturned a lower court ruling that had deemed the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) exceeded its authority in regulating ghost guns. Justice Neil Gorsuch, writing for the majority, emphasized that the regulation is consistent with existing law and necessary to adapt to modern firearm manufacturing trends. The ruling was supported by Chief Justice John Roberts and Justice Amy Coney Barrett, along with the court's three liberal members. Justices Samuel Alito, Brett Kavanaugh, and Clarence Thomas dissented, arguing that the regulation supports governmental overreach.

The decision reinforces the federal government's authority to regulate firearms assembled from kits or 3D-printed parts, aiming to curb their proliferation and enhance public safety. Law enforcement and gun safety groups praised the ruling, highlighting its importance for public safety. The regulation requires that ghost gun kits be regulated like traditional firearms, including serial numbers and background checks, which is expected to reduce their appeal to individuals seeking untraceable weapons.

Prior to this ruling, the regulation of ghost guns faced legal challenges. In 2023, U.S. District Judge Reed O’Connor in Fort Worth, Texas, struck down the rule, concluding that it exceeded the ATF's authority. The Supreme Court's recent decision overturns this ruling, affirming the ATF's ability to regulate ghost guns under existing federal law.

As of November 2024, 15 states have implemented regulations targeting ghost guns. These measures vary by state but generally include serial number requirements, background checks, reporting obligations, and restrictions on 3D-printed firearms. For example, California requires serial numbers and background checks for firearm components and mandates that all ghost guns be reported to officials.

The Supreme Court's decision is expected to have substantial implications for gun control policies and ongoing debates surrounding Second Amendment rights. By upholding the regulation, the Court has signaled support for measures aimed at preventing untraceable firearms from being used in criminal activities, thereby enhancing public safety. This ruling may also influence future legislative and judicial actions concerning firearm regulations and the balance between individual rights and public safety.

Solicitor General Elizabeth Prelogar, representing the administration, emphasized the public safety interests in reversing the flow of ghost guns to dangerous and otherwise prohibited persons, stating that these interests "easily outweigh the minor costs that respondents will incur."

David Pucino, deputy chief counsel of the Giffords Law Center to Prevent Gun Violence, praised the Supreme Court's action, stating, "The challenged rule simply requires that ghost gun kits are regulated like the guns that they are. It will save lives."

Cody J. Wisniewski, general counsel of the Firearms Policy Coalition Action Foundation, expressed disappointment, stating, "We’re deeply disappointed that the Court pressed pause on our defeat of ATF’s rule effectively redefining 'firearm' and 'frame or receiver' under federal law."