Federal Court Strikes Hawaii Statutue Outlawing Butterfly Knives

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In Teter v. Lopez, No. 20-15948 (August 7, 2023) the 9th Circuit Court of Appeals held that Hawaii’s criminal statute prohibiting possession of butterfly knives violates the second amendment. The 9th Circuit has jurisdiction over federal district courts in California, Idaho, Montana, Nevada, Oregon, and Washington.


In Hawaii, it is a misdemeanor to knowingly to manufacture, sell, transfer, transport, or possess a butterfly knife—no exceptions.

Plaintiffs Mr. Teter and Mr. Grell are law-abiding Hawaii residents who wished to purchase butterfly knives for self-defense. They sued Hawaii’s Attorney General and Sheriff Division Administrator (“Hawaii”). They sought to establish that Hawaii’s statute violates the Second Amendment.

The Plaintiffs further argued that, but for Hawaii’s law, they would purchase butterfly knives.  They owned butterfly knives before moving to Hawaii and were forced to dispose of their knives because of Hawaii’s ban on butterfly knives. The Plaintiffs’ expert witness agreed that the butterfly knife “is just a tool” that can be used offensively and defensively.


The 9th Circuit began by saying the butterfly knife, also known as the “balisong,” has a disputed origin. Some sources say it originated in France; others, the Philippines. It is anywhere from a few hundred to over a thousand years old. Regardless of its origin, the butterfly knife resembles an ordinary pocketknife, a tool that has been used by Americans since the early 18th century.

“Like a pocketknife, the butterfly knife comprises a handle and a folding blade, the cutting edge of which becomes covered by the handle when closed. Unlike a pocketknife, however, the butterfly knife’s handle is split into two components. Together, these two components fully encase the blade when closed and rotate in opposite directions to open. With a few short, quick movements, an experienced user can open a butterfly knife with one hand.” ~9th Circuit Court of Appeals

The 9th Circuit also held that possession of butterfly knives is conduct covered by the plain text of the Second Amendment:

“Bladed weapons facially constitute ‘arms’ within the meaning of the Second Amendment, and contemporaneous sources confirm that at the time of the adoption of the Second Amendment, the term ‘arms’ was understood as generally extending to bladed weapons, and by necessity, butterfly knives. The Constitution therefore presumptively guarantees keeping and bearing such instruments for self-defense.” ~9th Circuit Court of Appeals

Finally, the 9th Circuit reasoned that a butterfly knife is an “arm,” and more analogous to a pocket knife than historically prohibited bladed weapons such as Bowie knives or the Arkansas toothpick. With that, the 9th Circuit concluded that Hawaii’s law banning butterfly knives violates the Second Amendment.

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