A switchblade knife (also called a "switch" or "automatic knife") is a folding knife with a blade that swings from side to side on the inside of the handle when opened. The most famous type of this knife, and the holster for carrying it, is seen in numerous iconic images, such as photographs or illustrations from American crime magazines.

In some jurisdictions, these are illegal because they do not have enough safety features to allow them to be carried safely. However, legal restrictions vary greatly by location and intent of use; for example, hunting knives that are switchblades would not be regulated in many states. In some countries, they are still considered banned altogether due to their history as weapons used by criminals.

In the United States, some states have laws that legalize these blades (by a specific name), whereas in other states they have been made illegal. However, it is legal to sell and manufacture them for export. These knives were originally designed as tools for self-defense, fighting, or utility purposes such as opening cans of food. They were used in World War II by the U.S. infantry.

Detailed Overview of History

Working in a factory was a new life for many teens in the 1930s and 1940s. The switchblade knife was designed for quick, easy access when working, so it could be used as part of your daily routine without any hassle. The switchblade was invented by a New York City jeweler named William Marston who wanted to design a tool that would help him complete his work faster than before. 

He took an idea from an early twentieth-century French designer named Paul Thénard who had combined two flintlock pistols into one smaller Japanese sword knife. Marston called the two-blade gun he created a "Venus" and named the two-bladed knife he came up with the "Wonderful." He later renamed it "The Switchblade." The switchblade has been around for over 100 years and it never went out of style. It saw many changes throughout its history, but it still remains one of the most popular cool knives in our society today.

The switchblade is not a new invention by any means. In fact, these knives have been around since ancient times. The knife has been found in tombs as far back as early Egyptian times. Over the centuries, this type of knife has been used in different cultures around the world. The knife was also known as a "trench knife," or when they were called by their French name, "zig-zag" knives.

In 1941, a man named Ellsworth Fisher was able to patent a switchblade that wasn't just marketed to men. Fisher's original design was created in 1910 and he worked his way up from being an electrician for the New York Telephone Company to being recognized as an inventor by the New York State Department of Patents and Designs. In June of 1941, Fisher applied for a patent on his switchblade design and this achieved him widespread recognition.

Although William Marston applied for a patent on his knife, the knife went out of style in the 1900s when knives became more popular. He had to wait until 1941 to obtain a patent. The switchblade has a blade that springs out by using a liner lock mechanism. The liner lock is a type of locking mechanism that uses two detent balls within the knife's handle. 

The plastic or metal coating around the inside of the handle gives it an extra grip for increased control when handling the knife during use. Inside each ball is a spring-loaded retaining arm that presses back against its cam plate when you open the blade and it extends from the cam plate toward the point of attack.

Key Categories of Switchblade Knife

(Most) switchblades are one-hand opening knives, with an automatic safety lever that prevents loss of grip when opened to its full position. Very few (if any) have a locking feature that prevents closure when pushed from that position. 

  • Locking Mechanism

Some switchblades have a locking mechanism that prevents closure. Most lockable designs follow the same design as their non-locking cousins, having a small tab that protrudes from the knife's handle and into a notch in the blade to prevent closure if it is pushed from its normal closed position. While this may seem like it would be more secure than its non-locking cousin, there are two major problems with this design. 

First, is that it can still be closed if the knife's mechanism malfunctions (which is common on lockable knives). Second, if the tab breaks off, or is somehow forced out of its normal position, the knife can be closed on your hand.

  • Tolerable Safety Lever

Another design used is called a "tolerable safety lever". The tolerable safety lever is designed to prevent closure only when pushed past a certain point (as opposed to the small tab that protrudes from the handle and into a notch in the blade). 

It can still be closed manually if needed, so this feature should not be seen as an alternative to proper training when using these knives. This feature was first used by Al Mar and later copied by Spyderco, who calls this "directional control", available on their early SpydeSlikes and Slysz Bowie Knife.

  • Automatic Safety Lever

Out of the four design types, the automatic safety lever is the most common, utilized on all but one of these knives. There are a few examples of knives that utilize a different style of the lock mechanism.

  • Reopening Style

The most common type is the reopening device (also called a "safety", "quick-opening" or "automatic") which is used on switchblades (most are one-hand opening; some have the dual opening capability) and similar folding knives with manually deployed blades or multiple layers in their handles. 

This switchblade knife uses a small lever under the blade or within the handle to prevent closure during normal operation. To open, the user must purposefully move the lever past a certain point (usually the halfway point of the blade) and then release it. Upon release (or when it is deliberately engaged by pushing past that point), the knife opens automatically, at which point the lever resets to its original position.

  • Knife-Locking Style

The knife-locking type lock is widely used on folding knives with manually deployed blades or multiple layers in their handles. The locking mechanism is usually a flange on one side of the blade that protrudes under spring pressure from one lock opening position to another, blocking access to the lock opening cuts.

Pros and Cons of Switchblades

The switchblade, also called a flick knife or automatic knife, is one of the types of cool pocket knives with a button that helps to release the blade into position. It is often confused with the autostop (also called an auto sheath) – more expensive knives that contain an advanced retractable spring-loaded mechanism and safety locking system. Here are the pros and cons of a switchblade knife:

  • Pros

These knives are the strongest, sharpest, and most durable type of folding pocket knife. These knives are legal in most states except for California and New York and many people own switchblade knives as collector items. Some states allow these knives to be carried in the open but switchblades cannot be carried or concealed. 

Switchblades have been popular since before the 1920's with their invention credited to James Assinder and Jack Hobbs of England. The knife can be opened using one hand which makes it more convenient than other types of pocket knives that need both hands to open which makes it easier to use. 

  • Cons

These knives are illegal in some states and some countries and possession of a switchblade knife may result in jail time, fines, and confiscation of the knife under most jurisdictions. Switchblades can be dangerous in the wrong hands. The high cost of the switchblade is another con for many people.

The mechanism used to open a switchblade can be accidentally triggered resulting in injury to the person carrying or using it. Many people believe that switchblades are stealth weapons that can be easily concealed but this is untrue because switchblades are not easily concealed due to their size, shape, and the sound they make when opening.