The Supreme Court has upheld the ATF’s “ghost gun” kit ban, but its ruling was fairly narrow. So, what exactly does it do?

On Wednesday, a 7-2 majority ruled the Biden-era survived what it categorized as a facial challenge. It argued there was at least one scenario where the items the ATF targeted fit within the underlying statute: now-defunct Polymer80’s “buy build shoot” kit and its unfinished frames.

“Yes, perhaps a half hour of work is required before anyone can fire a shot,” Justice Neil Gorsuch wrote for the majority in Bondi v. VanDerStok. “But even as sold, the kit comes with all necessary components, and its intended function as instrument of combat is obvious. Really, the kit’s name says it all: ‘Buy Build Shoot.'”

Outside of that, though, the majority declined to give further specific guidance. It offered up a myriad of caveats about the potential limits of its ruling, but no bright lines on how far the ATF could reach under the rule it upheld.

“Admittedly, our reasoning here has its limits. Just because some kits, like Polymer80’s, qualify as ‘weapons’ that ‘can readily be converted’ into working firearms does not mean all do,” Gorsuch wrote of the “buy build shoot” kits. “Think of the problem of the heap: Start with a heap of sand and begin removing grains; at some point, a heap no longer exists. That problem attends many artifact nouns. Even when used to capture unfinished products, artifact nouns generally reach only so far. It would be extravagant to speak of a novel when the author has dashed off only a few lines. Few would call a pile of unfinished logs a table. Subsection (A) may present a similar problem.”

“Weapon parts kits vary widely,” he continued. “Not all come as complete as the ‘Buy Build Shoot’ kit. Some, too, may require more time, expertise, or specialized tools to finish. And at some point a kit may be so incomplete or cumbersome to assemble that it can no longer fairly be described as a ‘weapon’ capable of ‘read[y] . . . conver[sion]’ into a working firearm. While we recognize the problem, this case does not require us to untangle exactly how far subsection (A) reaches.”

He echoed the same basic point for Polymer80’s unfinished frames.

“Here, again, our reasoning has its limits. In saying that a product like Polymer80’s qualifies as a ‘frame,’ we do not suggest that the GCA reaches, and ATF may regulate, any combination of parts susceptible of conversion into a frame or receiver with sufficient time, tools, and expertise. Like the term “weapon,” the artifact nouns “frame” and “receiver” have their bounds. Some products may be so far from a finished frame or receiver that they cannot fairly be described using those terms. But this case requires us to explore none of that.”

Writing in concurrences and dissents, many of the justices seemed to disagree on what exactly the implications of the ruling should be.

One of the most prominent disagreements was between Justices Samuel Alito and Sonia Sotomayor. They went back and forth over what precisely the Court had to say about what the ATF could regulate.

“The second point I address is the suggestion that the Act permits ATF to regulate only ‘all-but-assembled’ weapon parts kits and frames ‘as close to completion as possible,'” Sotomayor wrote, apparently alluding to Alito. “The Court’s opinion speaks for itself on that point and others. I encourage readers to go to the source, rather than rely on dissents, to understand what the Court holds. It is the Court’s ruling, not the one set forth by the dissents, that binds the lower courts.”

Alito responded in kind.

“Although Justice Sotomayor obviously wishes that the Court had gone further, all that the Court has actually held is that the ATF rule is not facially invalid because at least some applications of the rule are consistent with the statute,” he wrote. “And the two examples that the Court cites are (1) a kit that contains all the parts needed to make a semiautomatic pistol and that can be assembled in 21 minutes and (2) a frame that can be made functional simply by clipping off two plastic tabs and drilling a few holes, ante, at 17–18, 21. The Court has not held that any other kits or presently non-functional receivers are covered.”

Then there was the disagreement over whether the majority’s reasoning could lead to AR-15 owners being subject to the National Firearms Act (NFA). That’s because Justice Clarence Thomas and the plaintiffs argued semi-automatic AR lowers could be considered as easily convertible to fully-automatic lowers as those Polymer80 frames are to finished frames. The majority argued the government had no interest in trying to make that connection, and its opinion doesn’t justify it either.

“The government represents that AR–15 receivers do not ‘qualify as the receiver of a machinegun.’ Nor, the government emphasizes, has ATF ever ‘suggested otherwise,'” Gorsuch wrote. “Much the same can be said of our reasoning today. As we have stressed, a statute’s text and context are critical to determining whether (and to what extent) Congress used an artifact noun to reach unfinished objects. And, without doubt, the NFA and the GCA are different statutes passed at different times to address different problems using different language.”

So, the ruling gives the ATF a green light to go after dealers of kits akin to the “buy build shoot” one. But it opens up a lot of potential as applied challenges, too. The majority didn’t seem to mind that, though.

“The plaintiffs argue only that § 478.11’s provision addressing weapon parts kits is facially inconsistent with the statute. The Fifth Circuit adopted the same view after coming to the unqualified conclusion that weapon parts kits can never satisfy the statute’s two tests,” Gorsuch wrote. “To resolve this case, it is enough to say those assessments are mistaken. Because at least some weapon parts kits satisfy both of subsection (A) ‘s tests, §478.11 is not facially invalid.”