The Fifth Circuit Court of Appeals just decided whether the Second Amendment protects silencers. It didn’t go the way gun-rights advocates hoped.

On Thursday, a three-judge panel upheld the conviction of a Louisiana Federal Firearms Licensee (FFL) for possessing an unregistered silencer, more accurately called a sound suppressor, in violation of the National Firearms Act (NFA). The panel determined suppressors do not count as “arms” under the Second Amendment.

“The use of a suppressor, as we noted above, is not necessary to the use of a firearm, so it is not protected by the plain text of the Second Amendment,” Chief Judge Jennifer Walker Elrod wrote in US v. Peterson. “The Second Amendment, therefore, is not offended by the NFA regulation, so we AFFIRM the district court’s denial of Peterson’s motion to dismiss.”

While Thursday’s ruling did not arise from a formal challenge by gun-rights activists, it nonetheless spells bad news for some of their policy goals. One of the longtime priorities for many in the gun-rights movement has been chipping away pieces of the NFA–the most onerous of the federal gun statutes–with the eventual goal of totally dismantling it. Suppressor deregulation has been at the forefront of those efforts for decades.

The federal government enacted the NFA and its restrictions on items like suppressors, short-barreled rifles, and machineguns more than 140 years after the Second Amendment was ratified. Some gun-rights advocates believe that a faithful application of the Supreme Court’s Bruen standard—which requires analogizing to Founding-era approaches to weapons regulation in order to support current gun laws—could eventually gut suppressor regulations and bring down the NFA altogether. However, the Peterson panel’s analysis never reached the point of performing Bruen‘s required historical analysis.

Instead, they stopped a step short of that. Using the definition considered by the Supreme Court in Heller, the panel set a baseline that “‘arms’ in the Second Amendment sense comprises ‘weapons of offence,’ ‘armour of defence,’ and ‘anything that a man wears for his defence, . . . takes into his hands, or useth in wrath to cast at or strike another.'”

While the defendant argued suppressors are “an integral part of a firearm” and thus should be given the same Second Amendment consideration as other weapons, the panel disagreed.

“A suppressor, by itself, is not a weapon,” Walker wrote. “Without being attached to a firearm, it would not be of much use for self-defense. And unless a suppressor itself is thrown (which, of course, is not how firearms work), it cannot do any casting or striking.”

Instead, she classified suppressors as firearm accessories, which she distinguished from “accoutrements” like gunpowder, lead, and cartridges considered protected by other courts. She argued those items are necessary for a firearm to function, whereas accessories like suppressors are merely compatible with firearm usage.

“While possession of firearms themselves is covered by the plain text of the Second Amendment, possession of firearm accessories is not,” she concluded.

The case highlights the difficulty gun-rights advocates will have in trying to undermine the NFA through judicial means. Even with a historically focused Second Amendment test, in a typically friendly circuit, they were stonewalled. And the odds the Supreme Court might step in to rule otherwise, even if they might disagree with the premise that accessories are unprotected, don’t look good.

The Court has already proven extremely hesitant to accept cases involving bans on far more common items like semi-automatic rifles and ammunition magazines. Furthermore, even if it did take the issue up, there’s no guarantee that the Court, as currently constituted, would rule the way gun-rights advocates want–no matter how incongruent with the Bruen standard advocates may think such an outcome would be.

In both the oral arguments and delivered opinion in the case over the ATF’s bump stock ban, multiple members of the Court’s conservative majority indicated they’d approve of bump stocks being banned by Congress. None even mentioned how they thought such a ban might fit with the Court’s own text, history, and tradition test. Bump stocks, like suppressors, could be construed as accessories and similarly sit outside the Overton window of what is considered a protected “arm” by the Court.

The most recent Second Amendment case the Court did take, US v. Rahimi, also showed that the justices may be willing to bend Bruen to avoid untenable public relations outcomes in controversial cases.

The Court’s Second Amendment jurisprudence has also tended to lag behind public opinion. Its few landmark decisions recognizing broader gun rights protections have all borne that out. While suppressors are becoming more mainstream and more widely owned, their acceptance by the broader public still falls far short of where handguns and concealed carry were at by the time the Supreme Court acted on those issues.

That’s not to say that courts may never be an avenue for success. There have certainly been sporadic Second Amendment victories in the lower courts against other controversial items regulated by the NFA. In the last year, for instance, at least two district court judges have struck down the general federal prohibition on machine guns as applied to particular criminal defendants. It’s also possible that other circuit court judges might see things differently in an en banc setting.

Indeed, at least one Fifth Circuit judge who was not on the Peterson panel previously dropped a few breadcrumbs to that effect in an earlier concurrence dealing with the ATF’s pistol-brace rule. In it, Judge Don Willett mused on the possibility that braces and other firearm accessories or attachments should be afforded constitutional protection on par with firearms themselves.

“In my view, protected Second Amendment’ conduct’ likely includes making common, safety-improving modifications to otherwise lawfully bearable arms,” Willett wrote in Mock v. Garland.

He also questioned the historical justification for certain aspects of the NFA as a whole.

“ATF has not identified any historical tradition of requiring ordinary citizens to endure a lengthy, costly, and discretionary approval process just to use accessories that make an otherwise lawful weapon safer,” he wrote.

But the fact remains that a panel of all Republican-appointed jurists in the most conservative and most pro-Second Amendment circuit court in the country concluded that suppressors, which are literally deemed firearms under federal law, do not count as “arms” protected by the Second Amendment.

That all indicates gun-rights advocates with ambitions of deregulating suppressors or abolishing the NFA may be forced to refocus their efforts outside the courtroom.