The new Biden administration’s rules to put “ghost guns” in the same legal category as conventional weapons on Wednesday, after a federal judge rejected a request to temporarily halt the change.

The regulations require that the main components used in the manufacture of ghost rifles – frames and receivers – be assigned serial numbers. They also require buyers to conduct background checks before buying the kits and require dealers to have a federal license to sell the kits and keep sales records.

The law, announced in April by the White House, came into effect despite prosecutors ordering the Bureau of Alcohol, Tobacco, Firearms and Explosives to stop enforcement.

On Tuesday, U.S. Chief Judge Peter Welte in North Dakota denied a request for a preliminary or permanent injunction as part of a lawsuit filed by the state’s Republican attorney general, gun groups and a gun store owner. The judge ruled that Biden’s law “is and continues to be constitutional under the Second Amendment.”

In a federal lawsuit filed in Texas, a judge ruled that the retailer’s prediction that Section 80 of the law would “disrupt” its entire operation was insufficient to sustain the company’s request to block the rule nationwide.

The National Rifle Association, the nation’s largest gun rights group, criticized the rules.

In recent years, the sale of ghost gun kits has become a concern for all levels of law enforcement. From the federal Department of Justice to city police departments, officials are struggling to curb the spread of these weapons, which are being returned to crime scenes across the country. According to the White House, there were nearly 20,000 dead gun recoveries reported to the ATF last year alone.

“These guns are often sold as do-it-yourself kits that include all or nearly all the parts needed to quickly build an unmounted gun,” Attorney General Merrick Garland said in a statement Wednesday.

“That changes today. This law will make it harder for criminals and other prohibited persons to obtain guns that are not available to them,” he said. “It will help ensure law enforcement officers have access to the information they need to solve crimes. And it will help reduce the number of unidentified firearms flooding our communities.”

In recent weeks, ghost gun retailers have been scrambling to unload their inventory before the deadline, with some online dealers selling out completely.

In addition to the new federal law, several states and territories, including California, Connecticut, Hawaii, New Jersey, New York, Rhode Island, Washington and the District of Columbia, restrict or ban assault rifles.