The Denver-based federal appeals court issued a mixed decision on Thursday, finding that a group of plaintiffs could not challenge certain aspects of Colorado’s “ghost gun” prohibition, could challenge others, and ordered further analysis of the law’s constitutionality.

To address the proliferation of guns privately assembled from kits or 3-D printers, the General Assembly enacted Senate Bill 279 three years ago, making it a misdemeanor to possess certain firearm components not imprinted with a serial number. There is an exception when the owner obtains a serial number from a licensed firearm dealer and the dealer performs a background check. Multiple violations of the law are felony offenses.

After a collection of gun rights groups and individual plaintiffs failed to receive a preliminary injunction, they turned to the U.S. Court of Appeals for the 10th Circuit. In an April 23 opinion, a three-judge panel addressed the law’s manufacturing prohibition, the possession component, and the purchasing component.

All three judges agreed that the prohibition on manufacturing a firearm frame or receiver did not apply to what the plaintiffs wanted to do — assemble parts that were already manufactured.

The law “limits the prohibition to making frames or receivers from raw material — not the completing, assembling, or converting a previously manufactured and unfinished frame into a finished one,” wrote Judge Joel M. Carson III in concluding the plaintiffs could not challenge the manufacturing component.

As for the prohibition on acquiring gun parts, U.S. District Court Judge Gordon P. Gallagher initially denied a preliminary injunction after observing that a federal rule from the Bureau of Alcohol, Tobacco, Firearms and Explosives similarly required the inclusion of serial numbers on gun parts to facilitate the tracing of firearms used in crimes. That requirement would remain in place even if Colorado’s law were to be blocked, he reasoned.

At the same time, Gallagher noted the U.S. Supreme Court was poised to consider whether the ATF had the authority to regulate gun components as “firearms” in a challenge that originated from Texas.

“It is conceivable that, during the next term, the Supreme Court could determine that the ATF exceeded its congressionally delegated authority,” acknowledged Gallagher, a Joe Biden appointee. “As of now, however, the governing federal law renders this claim too speculative.”

Although the Supreme Court declined to overturn the federal regulation last year, the 10th Circuit panel determined Colorado’s law prohibited more conduct than the federal regulation. Specifically, the majority believed the plaintiffs could challenge the state prohibition on purchasing unserialized firearm kits from individuals.

Carson wrote that even if the plaintiffs did not say they planned to acquire guns in that fashion, they had alleged they were “law-abiding citizens” who wanted to continue purchasing firearm kits.

“This is sufficient to show that a favorable judgment could redress the alleged injuries flowing from Plaintiffs’ acquiring-prohibition claims,” wrote Carson for himself and Judge Allison H. Eid, both first-term appointees of President Donald Trump.

Senior Judge Paul J. Kelly Jr. disagreed, writing that there was “no indication” the plaintiffs intended to obtain unserialized firearm parts from individuals.

“Here, there is a real question as to whether there is a supply of unserialized, unfinished frames from private individuals, particularly given the legal landscape and the current federal regulation requiring serialization,” wrote Kelly, a George H.W. Bush appointee.

Finally, the panel disagreed with Gallagher that the challenged law did not implicate the plaintiffs’ Second Amendment rights.

The law “imposes a condition on the commercial sale of a firearm,” Gallagher had written. It “does not prevent an individual from buying an unfinished frame or receiver or firearms part kit and in no way infringes upon Plaintiffs’ right to acquire arms. Rather, the Statute requires the purchaser to have the frame or receiver serialized.”

The 10th Circuit’s majority disagreed that the law simply attached conditions to firearm sales.

The provisions “regulate unserialized frame and firearm possession — no matter how a person previously acquired the frame or firearm,” wrote Carson for himself and Eid.

The majority concluded Gallagher was wrong to deny an injunction for that reason. The panel returned the case to him for further analysis.

Kelly, in dissent, indicated he would have allowed Gallagher to determine whether more recent Second Amendment decisions from the 10th Circuit would lead him to reach a different conclusion about the nature of the law.

The case is National Association for Gun Rights et al. v. Polis.