Since 1999, the butterfly knife has been legally banned in Hawaii. No more.

Last week, the 9th U.S. Circuit Court of Appeals elevated butterfly knives to the status of constitutionally protected “arms” as defined by the Second Amendment.

And while the decision addressed only Hawaii’s law, state officials and the Legislature should take note: The implications could be far broader. Some legal experts posit that the court has opened the door to lift state-imposed restrictions on other non-firearm weapons, like switchblades.

Writing for a three-judge panel, Judge Carlos Bea wrote: “Because the possession of butterfly knives is conduct protected by the plain text of the Second Amendment, and because Hawaii has not demonstrated that its ban on butterfly knives is consistent with this Nation’s historical tradition of regulating arms, we conclude that section 134-53(a) violates Plaintiffs’ Second Amendment rights.”

The court applied the new historical tradition test created by the U.S. Supreme Court in New York State Rifle & Pistol Association v. Bruen, the June 2022 ruling which held that government regulation must be “consistent with the nation’s historical tradition of firearm regulation.”

Bruen forced Hawaii and other states to relax virtual bans on concealed carry of firearms. As a result, the counties have started to issue permits; as of Aug. 2, the Honolulu Police Department had issued 409. Given the new Bruen reality, the city and state wisely passed laws restricting where guns could be carried, to keep them out of sensitive public places.

They should consider doing the same with other weapons, because, while Bruen dealt with a firearms restriction, Bea wrote, “We see no reason why the (Bruen) framework would vary by type of ‘arm.’”

This suggests that other weapons currently banned or restricted by Hawaii and other states could become readily available, to own and to carry in public. It also suggests that states have less leeway in reaching their own conclusions about public safety when it comes to dangerous weapons.

Hawaii’s Legislature in 1999 moved to ban butterfly knives, which were readily available at swap meets, because they were perceived to be a public threat. Juvenile girls picked up for truancy had them in their purses, and more juvenile boys were using them to commit robberies and threaten classmates, police said.

“Butterfly knives are preferred as they are easy to conceal and are more intimidating when brandished,” said Capt. George McKeague, who was head of HPD’s Criminal Investigations Division in 1999.

But rather than defer to the state’s judgment, or grant the state’s request for further review of the historical tradition question, the Ninth Circuit appellate panel dismissed it: “The butterfly knife is simply a pocketknife with an extra rotating handle,” and not a novel dangerous weapon beyond the comprehension of constitutional drafters.

Such worries about butterfly knives may seem quaint now, what with people packing guns. But uncertainty about a government’s ability to regulate dangerous weapons can be a public safety problem. For example, ghost guns, built with kits and untraceable, have become more popular among criminals, including in Hawaii. Thankfully, the U.S. Supreme Court ruled earlier this month that the Biden administration could continue to closely regulate the weapons — temporarily, pending court challenges.

While the post-Bruen legal landscape remains murky, state officials must be vigilant about doing what they can to keep dangerous weapons at bay. That would include jealously guarding Hawaii’s ability to keep our communities safe, even if it requires going to court.