A federal appeals court on Thursday ruled that the Biden administration lacked authority to adopt a regulation aimed at reining in privately made firearms called “ghost guns” that are difficult for law enforcement to trace.

A three-judge panel of the New Orleans-based 5th U.S. Circuit Court of Appeals sided with a group of firearm owners, gun rights groups and manufacturers in declaring the Bureau of Alcohol, Tobacco, Firearms and Explosives’ 2022 rule “unlawful.”

The panel, comprised entirely of judges appointed by Republican former President Donald Trump, largely upheld a Texas judge’s ruling against the rule, which targeted the rapid proliferation of such homemade weapons.

The rule updated the definition of a “firearm,” “frame” and “receiver” under the Gun Control Act of 1968 to address the rise of ghost guns that can be assembled from kits that can be bought online or at a store without a background check.

U.S. Circuit Judge Kurt Engelhardt, writing for the 5th Circuit panel, said ATF’s rule “flouts clear statutory text and exceeds the legislatively-imposed limits on agency authority in the name of public policy.”

“ATF, in promulgating its final rule, attempted to take on the mantle of Congress to ‘do something’ with respect to gun control,” he wrote. “But it is not the province of an executive agency to write laws for our nation.”

Read Related Also: National World War II Museum in New Orleans opens $400 million honorary Liberty Pavilion ahead of Veterans Day

The U.S. Department of Justice and ATF did not respond to requests for comment. But the administration is likely to appeal, after already seeking the U.S. Supreme Court’s intervention in the case.

The Supreme Court had twice before in August and October acted following rulings by the Texas judge and granted requests by the administration that have allowed the regulations to remain in effect while litigation continues.

The administration has said that ghost guns are attractive to criminals and others prohibited from lawfully buying firearms, including minors.

There were about 20,000 suspected ghost guns reported in 2021 to the ATF as having been recovered by law enforcement in criminal investigations — a tenfold increase from 2016, according to the White House.

Cody Wisniewski, a lawyer for the plaintiffs at the Firearms Policy Coalition Action Foundation, in a statement called Thursday’s ruling a “massive victory against ATF and a huge blow to the Biden administration’s gun control agenda.”