The regulation is aimed at kits sold online that can be converted into functional weapons in under 30 minutes.
The Supreme Court will hear a challenge Tuesday to a Biden administration regulation targeting ghost guns.
Ghost guns are untraceable firearms assembled from kits that have been increasingly linked to crime in recent years.
The regulation is aimed at kits sold online that can be converted into functional weapons in under 30 minutes. The completed weapons, lacking serial numbers, are nearly impossible for law enforcement to trace.
The new law mandates that the kits be treated like traditional firearms, which includes adding serial numbers, conducting background checks, and ensuring buyers are at least 21 years old.
The rule was implemented through an executive action from President Joe Biden.
Ghost gun seizures by police jumped from under 4,000 in 2018 to nearly 20,000 in 2021, according to the Justice Department.
Since the regulation took effect, the number of ghost guns recovered in cities like New York, Los Angeles, Philadelphia, and Baltimore has either plateaued or declined, according to court filings.
