What’s An Automatic Knife? Are They Illegal?

You’ve probably seen the Italian Stiletto switchblade being wielded by a bad guy in a Hollywood film. The Stiletto is an Automatic Knife, a type of spring-loaded pocket knife that was criminalized by newspapers in the 1950s. Congress even sought to restrict their manufacture and sale with the Federal Switchblade act in 1958.

This guide is not legal advice. If you’re not sure whether automatic knives are legal in your state, contact a local attorney.

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Q: What is an Automatic Knife?

A: An automatic knife deploys its blade under its own power when the user pushes a button. The blade in an automatic knife is under constant spring tension, with a lock keeping the blade held inside the handle. When the blade’s button is pushed, the lock disengages and the blade opens in the blink of an eye. Automatic knives either open from the side of the handle, or out the front of the handle (“OTF”).

How a Side-Opener Works

Pictured: Kershaw Launch 4 Side-Opening Automatic

In a side-opening auto knife, one side of the blade rests against a spring. The spring is compressed when the blade is closed. The spring’s tension is always pushing against the side of the blade, ready to force it out of the handle into the open position. The blade and spring are held in place by a plunger. When the knife’s button is pressed, the plunger disengages, allowing the blade to to be pushed open by the spring, releasing its tension. Closing the blade compresses the spring, making it ready for the next release.

How an OTF Knife Works

Pictured: Microtech “Ultratech” OTF Automatic

OTF knives are single-action or double-action. Like a side-opener, the single-action OTF blade is held inside the handle by a plunger, with a compressed spring resting against the bottom of the blade. When the blade’s button is pressed, the plunger releases the blade, and the spring’s tension forces the blade out the front of the handle.

Double-action OTF knives can be opened and closed automatically, without the user having to manually close the blade to recompress its spring. Instead, the blade slides on a rail, with a spring that is tensioned by the user pressing on two-way push mechanism. When the user presses the mechanism forward, tension builds in the spring by stretching it, until the mechanism releases a plunger.

Once the plunger is disengaged, the stretched spring snaps forward and releases its tension, pulling the blade and launching it out of the handle. To close the knife automatically, the same mechanism works in reverse, creating spring tension until the plunger disengages and snaps the blade back into the handle.

Q: Are Switchblades and Automatic Knives the Same?

A: Yes, the terms “automatic knife” and “switchblade” are used interchangeably in casual conversation, and in state and federal laws. There are other terms used to reference an automatic knife, including “switch knife,” “pushbutton knife,” ejector knife,” “flick knife,” “Stiletto,” and “spring knife.”

(Not All Spring-Assisted Knives are Automatic)

Some spring-assisted folding knives are incorrectly called switchblades or auto knives. If a spring-assisted knife requires the user to open the blade by overcoming spring tension (rather than by merely releasing stored spring tension) then it the knife in question is neither a switchblade nor an automatic knife.

Pictured: SOG Flare Folder

The SOG Flare Folding Knife is a great example of this not-a-switchblade. A small piece of curved spring steel in the handle keeps pressure on the blade when closed, preventing accidental release. The user must push on the thumb stud to overcome this spring tension. Once the tension is overcome by the user, the spring steel will reverse the direction of its curve and suddenly apply tension against the blade, assisting with its opening action. This is often called a “bias-toward-closure” or “assisted-opening” knife.

Q: Are Automatic Knives Illegal Under Federal Law?

A: Federal law does not prohibit the possession of automatic knives and switchblades in the U.S. The Federal Switchblade Act only outlaws the possession of switchblades and automatic knives on Native American reservations and territories including Puerto Rico, Guam, the U.S. Virgin Islands, the American Samoa, the Northern Marianas, and on Navy vessels and government aircraft.

How Federal Law Defines Switchblades

The official text of the Switchblade Act (U.S.C. Title 15, Chapter 29) defines a switchblade as any knife with, “A blade that opens automatically, either by pressure on a button or other device, or operation of inertia, gravity, or both.”

Exceptions to the definition include, “A knife that contains a spring, detent, or other mechanism designed to create a bias toward closure of the blade and that requires exertion applied to the blade by hand, wrist, or arm to overcome the bias toward closure to assist in opening the knife.”

That last part means spring-assisted knives (like the SOG Flare) are legally not considered switchblades under federal law.

Q: Which States Have Banned Automatic Knives?

A: The following states have outlawed the possession of automatic knives:

  • Delaware: § 1446 says selling and possessing switchblades is illegal.
  • Minnesota: Section 609.66 says making, transferring, or possessing a switchblade is a misdemeanor.
  • New Jersey: Section 2C:39-3 says possessing a switchblade or stiletto is a crime of the fourth degree.
  • New Mexico: § 30-7-8 says any knife which has a blade that opens automatically is unlawful to possess.

The following states have placed restrictions on automatic knives:

  • California: Blade must be less than 2″ in length.
  • Colorado: Concealed blades cannot measure more than 3.5″ in length.
  • Connecticut: Blade cannot measure more than 1.5″ in length.
  • Illinois: Can only be possessed with a valid Firearms Owner’s ID Card.
  • Maryland: Legal, but concealed carry is prohibited.
  • Massachusetts: Blade cannot measure more than 1.5″ in length.
  • New York: Can only be possessed by law enforcement or while hunting, trapping, or fishing with a valid license.
  • North Carolina: Legal, but concealed carry is prohibited.
  • North Dakota: Blade cannot measure more than 5″ in length.
  • Vermont: Blade must be less than 3″ in length.
  • Washington: Can only be possessed by law enforcement and emergency personnel.
  • West Virginia: Must be 21 years of age to possess.

Q: Did Pennsylvania Legalize Switchblades?

A: Yes, Pennsylvania repealed its switchblade ban on January 2nd, 2023. The state legislature passed House Bill No. 1929 and Governor Tom Wolf signed the bill into law. This bill removed any “dagger, knife, razor or cutting instrument, the blade of which is exposed in an automatic way by switch, push-button, spring mechanism, or otherwise” from the list of prohibited “Offensive Weapons” in the state’s criminal code.

Did you know a lot of folks also think gravity knives are illegal? They’re wrong (mostly). Be a know-it-all and read our Guide to Gravity Knives!