Joe Biden's attempted crackdown on so-called "ghost guns" has been ruled unlawful by the Fifth Circuit appeals court. 

In a unanimous ruling, a three-judge panel of the Fifth Circuit rebuked Biden for trying to re-write federal gun law.

"ATF, in promulgating its Final Rule, attempted to take on the mantle of Congress to 'do something' with respect to gun control. But it is not the province of an executive agency to write laws for our nation. That vital duty, for better or for worse, lies solely with the legislature," the court wrote.

Appeals court strikes Biden

Biden has attacked privately made firearms, often called "ghost guns" by gun control advocates, as a dangerous loophole in federal gun regulation.

His solution was to issue a rule through the Bureau of Alcohol, Tobacco, and Firearms (ATF) that treats non-functioning gun components like fully functioning firearms.

The new rule includes weapon parts kits in the definition of "firearm" and adds "partially complete, disassembled, or nonfunctional frame or receiver" to the definition of "frame or receiver."

The appeals court concurred with the finding of a lower court that Biden's expansive definition of "firearm" was simply too broad.

“It purports to regulate any piece of metal or plastic that has been machined beyond its primordial state for fear that it might one day be turned into a gun, a gun frame, or a gun receiver,” wrote judge Andrew Oldham in a concurring opinion. “And it doesn’t stop regulating the metal or plastic until it’s melted back down to ooze.”

Supreme Court awaits

Just in case Biden forgot how the Constitution works, the court emphasized the exclusive law-making power of Congress.

"Only Congress may make the deliberate and reasoned decision to enact new or modified legislation regarding firearms based on the important policy concerns put forth by ATF and the various amici here," the court wrote.

"But unless and until Congress so acts to expand or alter the language of the Gun Control Act, ATF must operate within the statutory text’s existing limits. The Final Rule impermissibly exceeds those limits, such that ATF has essentially rewritten the law," the ruling continued.

It now appears likely that the matter will head to the Supreme Court. Previously, the Supreme Court allowed Biden's rule to remain in effect while it went through the appeals process.

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