A case on ‘ghost guns’ has gone to the U.S. Supreme Court. Ghost guns are homemade guns that are unserialized and therefore untraceable. Gun rights groups are challenging a regulation brought in under the Biden administration which says that companies selling separate components of a gun must follow the same rules as those who are selling traditional, fully constructed firearms. This includes carrying out background checks on buyers and adding serial numbers to the DIY kits.

Manufacturers and pro-gun groups say that the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is overstepping its authority by reclassifying gun kits and gun components as firearms, claiming that such weapons kits do not meet the “firearm” definition under law. Anti-gun groups warn, however, that if the restriction is overturned, so-called ghost gun kits could be sold to teenagers, criminals and people with a history of mental illness.

Data compiled by Everytown Research and Policy shows that fifteen states in the U.S. already have regulations on ghost guns. In each of these, it is required to provide serial numbers for gun components, while background checks on buyers are also compulsory in most. In Washington, New York, Connecticut, New Jersey, Rhode Island, Oregon, Delaware and Hawaii, there is an additional ban on plastic undetectable guns and/or 3D printed guns. Meanwhile, in the states of Massachusetts, Rhode Island, Connecticut, New Jersey, Maryland, California and Hawaii, all ghost guns must also be reported to officials. In Delaware and New Jersey, the distribution of 3D printing instructions is also banned.

This article originally appeared on Statista.com and was syndicated by MediaFeed.org.