The Difference Between A Switchblade and an Assisted-Opening Knife

Photo credit: Iamthawalrus9 at Wikimedia Commons

Photo credit: Iamthawalrus9 at Wikimedia Commons

In the upcoming trial of the officers who arrested Freddie Gray, the case is undoubtedly going to revolve around whether the knife Gray was carrying was, in fact, a switchblade or an assisted-opening/spring-assisted knife. What is the difference between a switchblade, sometimes called an automatic knife, and an assisted opener? While both types of knives employ a spring when opening the blade, they are actually very distinct in the way they operate.

By far the most thorough explanation I have seen comes from our friends at

Switchblade knives have a bias towards opening; the blade is trying to open due to the spring being under tension or compression (depending upon the design). The only thing that keeps the blade from opening is the latch that keeps the blade in the closed position inside the handle of the knife.

Applying pressure on a “button or other device in the handle,” such as pushing down on the button with your thumb, releases the latch and the blade automatically opens. Your finger or hand never touches the blade.

Spring-assisted knives, and virtually all common folding knives for that matter, have a bias towards closure. This is a safety mechanism that prevents the blade from opening in your pocket. A spring or detent or similar mechanical mechanism helps to keep the blade closed until you physically open the blade by “exertion applied to the blade by hand, wrist, or arm to overcome the bias toward closure.”

In a typical spring-assisted knife, the blade must be moved 20-30 degrees open before the spring takes over to finish opening the blade, hence “spring-assist” or “assisted-opening.” The most common style of spring-assisted knife will have a stud on, or hole in the blade that you set your thumb onto or into and by moving your thumb, you rotate the blade open (other styles exist, but the principles remain the same). Once the blade moves past the bias towards closure and has been partially opened, the spring takes over to finish opening the blade.”

Furthermore, in 2009, President Obama signed into law amended language to the 1958 Federal Switchblade Act that specifically protects assisted-opening and one-hand opening knives. Here are the relevant sections with emphasis added in bold.

15 U.S.C.A. § 1241. Definitions

 As used in this chapter–

 (b) The term “switchblade knife” means any knife having a blade which opens automatically

(1) by hand pressure applied to a button or other device in the handle of the knife,

15 U.S.C.A. § 1244. Exceptions

 Sections 1242 and 1243 of this title shall not apply to

 (5) 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.

The issue seems pretty cut and dry, but in the case of Baltimore (and other municipalities), the way the local law is written leaves more wiggle room for prosecutors. Always check your local regulations.

In his arresting documents, the officer described Gray’s knife as a “spring assisted, one hand operated knife.” Until  information about the make and model of his knife is released we will not be certain whether it is a switchblade or the more common assisted-opener, but the officer’s description points to the latter.

 DISCLAIMER: I am not a lawyer and the above is not legal advice.


  1. Marjie says:

    I just came across your site now while trying to learn more about knives. I didn’t know that there was so much to learn about them. I’ve definitely gotten a lot more confused since because there’s so much into them.

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The Difference Between A Switchblade and an Assisted-Opening Knife

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