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The 21 Foot Rule can save your life

Dan Inosanto demonstrates how someone armed with a handgun can be killed by a knife wielder, if they begin 21' apart or less.

This article is part of a larger effort to understand what works, by observing the application of martial arts outside the arena. If you found it useful or interesting, check out more stories on:
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There is an old saying, "Never bring a knife to a gunfight." But that is not always true, at all.

Dan Inosanto is arguably the most knowledgeable man in martial arts. After over 70 years in the field, Inosanto teaches The Art and Philosophy of Jeet Kune Do, Filipino Martial Arts, Shoot Wrestling, Brazilian Jiu-Jitsu, Eskrima, Muay Thai, Silat, and mixed martial arts, among others,

An early black belt under Ed Parker, Inosanto later became both a student of and teacher to Bruce Lee. Inosanto also studied with dozens of different martial arts masters across the United States, Southeast Asia, and Europe, including Johnny Lacoste, Chai Sirisute, Jean-Jaques Machado, and  Yori Nakamura.

Inosanto, of Philippine descent, is particularly knowledgable in edged weapons. The US Army learned a harsh lesson about blades when the USA had control of the Philippine archipelago - a handgun may not be enough.

During the American occupation of the Philippines in the early 1900s, Moros, marked by tiger-eyes and red headbands - signifying a resolve to kill until killed - strode singly down the streets blading everything in their path, embracing the belief that every slain Christian assured their places in heaven. So tenacious was the Moros’ rampage that hundreds of reports by American soldiers surfaced, stating that the slugs of .38-caliber pistols failed to stop the advancing Moros. As a result of those reports, the .45-caliber pistol was designed and issued to American servicemen.

In the video below, Inosanto demonstrates how even someone armed with a handgun can be killed by someone armed with a knife, if they begin 21 feet apart or closer. And of course, many altercations take place well within this distance.

Although primarily a tool for law enforcement, the 21 Foot Rule, also known as the Tueller Phenomenon, and more accurately thought of as a guideline than a rule, has implications for civilians who carry a firearm, and for all of us.

The Tueller Phenomenon states that:
A determined knifer, with knife in hand and intent on cutting an officer whose sidearm is holstered, can successfully cut his victim if he starts within 21 feet of his intended victim.

You can watch it in action here:

The video above is an excerpt from Surviving Edged Weapons: How to Defeat Today's Fastest Growing Threat (Intended for Law Enforcement Only) produced by Dennis Anderson, and starring Dan Inosanto and Leo Gaje Jr. It is available from Amazon, in VHS.

This is the whole video:

Countless other efforts have confirmed it, including the Mythbusters guys:

And it made an appearance on the award-winning documentary series Justified:

This is a serious study of the subject, and remember, there is no element of surprise:

The Tueller Phenomenon/Drill was developed in the early 1980s by Sergeant Dennis Tueller, of the Salt Lake City Police Department. Similar to the Mythbusters episode, Tueller had two LEOs stand back to back; one had a handgun holstered, and the other had a knife in hand.

At a signal, one sprinted forward, and the other drew, aimed, and fired at a target (180 degrees from the sprinter). Upon hearing the report from the handgun, the sprinter froze.

It took 1.5-1.7 seconds for the shooter to draw, aim, fire, and successfully hit the target. During that time, the knife-wielder could sprint 20 feet, starting from a dead stop. Add in another foot to cover the reach of an arm, and The Tueller Phenomenon was born. 

In reality, there are more factors including the knife wielder's athleticism and skill with a knife, and the shooter's accuracy and reaction time under stress. Further, it is not always an either/or, because bullets aimed toward center mass don't necessarily have the stopping power that is typical of movies. Consider, for example, this scene from the 1974 Turkish martial arts documentary Kareteci Kiz.

So the Tueller Phenomenon is not so much a rule as a very clear warning - an assailant holding a blade, within 21 feet of you, is potentially a lethal threat, even if you have a holstered sidearm. Firearms are often thought to negate the need to learn unarmed hand-to-hand combat, but a gunner within the 21-foot margin would do well to know hand-to-hand knife defense. Your life could depend on it.

Discuss the 21 Foot Rule at