The Blade of Bruen: Fifth Circuit’s Switchblade Ruling Tests the Limits of “Arms” Under the Second Amendment

When History Meets Hardware

The Fifth Circuit has extended the Supreme Court’s Second Amendment jurisprudence into uncharted territory, striking down the Federal Switchblade Act as unconstitutional under the history-and-tradition test established in New York State Rifle & Pistol Ass’n v. Bruen, 597 U.S. 1 (2022). The ruling marks the first time a federal appellate court has applied Bruen’s framework to invalidate a weapons statute targeting blades rather than firearms, and it forces practitioners to confront a question the Supreme Court has conspicuously avoided: just how far does the term “Arms” extend beyond guns?

The decision, reported by Reuters on October 25, represents more than a niche victory for knife enthusiasts. It demonstrates that lower courts are reading Bruen not as a gun-specific ruling but as a categorical reset of how government may regulate any instrument that fits the Second Amendment’s text. For criminal defense attorneys, the ruling opens immediate avenues for challenging federal and state knife prosecutions. For prosecutors, it signals that the post-Bruen landscape is even more treacherous than anticipated.

The Statutory Target

The Federal Switchblade Act, codified at 15 U.S.C. §§ 1241–1245, prohibits the manufacture, transportation, and sale of switchblade knives in interstate commerce. Enacted in 1958 amid moral panic over juvenile delinquency, the statute has long been an oddity—federal law criminalizing a class of knives while leaving regulation of far deadlier weapons to the states. The Act defines “switchblade” broadly to include any knife with a blade that opens automatically by hand pressure applied to a button or other device in the handle.

The Fifth Circuit’s ruling holds that this prohibition cannot survive Bruen’s two-step framework. Under Bruen, when the Second Amendment’s plain text covers an individual’s conduct, the Constitution presumptively protects that conduct. The government must then justify the regulation by demonstrating it is consistent with the Nation’s historical tradition of firearm regulation. The Fifth Circuit concluded that switchblades constitute “Arms” within the meaning of the Second Amendment and that the government failed to identify a historical tradition of prohibiting such knives.

Why This Matters Beyond Knives

The immediate practical impact is narrow: federal switchblade prosecutions in the Fifth Circuit are now dead on arrival. But the analytical framework the court employed has sweeping implications. If switchblades are “Arms,” what about stun guns, nunchucks, or brass knuckles? The Ninth Circuit already held in Caetano v. Massachusetts, 577 U.S. 411 (2016) (per curiam), that stun guns fall within the Second Amendment’s scope, but Caetano predated Bruen and offered little guidance on methodology. The Fifth Circuit’s ruling suggests that any weapon commonly possessed for lawful purposes may now enjoy constitutional protection, regardless of whether it fires a projectile.

For criminal practitioners, this creates both opportunity and uncertainty. Defense attorneys should immediately review pending cases involving weapons charges under statutes that have never been subjected to Bruen scrutiny. State laws banning particular knife types, blade lengths, or carrying methods are now vulnerable. Conversely, prosecutors must be prepared to marshal historical evidence justifying such regulations—a burden that, as Bruen itself demonstrated, can be nearly insurmountable when the regulated item was not subject to comprehensive prohibition at the founding or during Reconstruction.

The Circuit Split Conundrum

The Fifth Circuit’s decision creates tension with other circuits that have upheld knife regulations post-Bruen. While no other federal appellate court has squarely addressed the Switchblade Act, several have rejected Second Amendment challenges to knife laws by reasoning that knives are not “Arms” protected by the Amendment or that historical regulations support modern restrictions. This emerging split increases pressure on the Supreme Court to clarify Bruen’s scope.

The Court has shown little appetite for such clarification. Since Bruen, the justices have denied certiorari in numerous cases involving Second Amendment challenges to non-firearm regulations, leaving lower courts to muddle through. The Fifth Circuit’s ruling, however, may prove harder to ignore. By invalidating a federal statute, the decision creates a direct conflict with the government’s enforcement authority and raises the stakes beyond individual state prosecutions.

The Historical Method’s Limits

The ruling also exposes the methodological challenges of applying Bruen to weapons that barely existed in recognizable form at the founding. Switchblades as we know them emerged in the mid-19th century, and mass-produced automatic knives are a 20th-century phenomenon. The Fifth Circuit’s analysis necessarily relied on analogical reasoning, comparing switchblades to historical blades and finding no tradition of categorical prohibition. But this approach highlights Bruen’s fundamental tension: how does one apply a history-and-tradition test to technologies that postdate the relevant historical periods?

Justice Barrett flagged this problem in her Bruen concurrence, warning that “history is not a regulated party’s playbook.” The Fifth Circuit’s switchblade ruling demonstrates that lower courts are taking her at her word, refusing to let the absence of historical regulation become a per se justification for modern restrictions. This interpretive move, while faithful to Bruen’s text, risks transforming the Second Amendment into a one-way ratchet that locks in the regulatory status quo of 1791 or 1868, regardless of technological change.

Strategic Implications for Practitioners

Criminal defense attorneys should treat the Fifth Circuit’s ruling as a template for challenging weapons statutes that have escaped post-Bruen scrutiny. The key is identifying weapons that were commonly possessed for lawful purposes historically and demonstrating the absence of a regulatory tradition. This requires investing in historical research and expert testimony—costs that may be prohibitive in routine cases but could pay dividends in strategic litigation.

Prosecutors, meanwhile, must develop historical justifications beyond mere public safety rationales. Bruen explicitly rejected means-end scrutiny, and the Fifth Circuit’s ruling confirms that lower courts are taking that prohibition seriously. Building a historical record early in litigation is now essential, as is identifying analogous historical regulations that can serve as valid comparators.

The switchblade ruling is unlikely to be the final word. But it is a clear signal that the Second Amendment revolution unleashed by Bruen is still in its early stages, and its reach extends well beyond firearms. Practitioners who fail to adapt do so at their clients’ peril.