The Fifth Circuit determined the Federal Switchblade Act cannot stand under the Second Amendment, as automatically opening knives are arms commonly used for defense.

Knives served defensive purposes from colonial times through the 1800s, when they formed a standard part of everyday carry. Precursors to modern switchblades have existed for centuries to permit quick opening with wet or gloved hands and were fitted to certain flintlock pistols in case of misfire.

Large-scale U.S. production began in the 1880s after postwar patents, involving about twenty manufacturers over the following fifty years. Millions of these knives circulate now and see lawful everyday, hunting, fishing, and recreational use despite the federal statute.