I recently was involved in a group discussion about 21 feet and a knife wielding attacker. In the discussion the participants were working to figure out when it is appropriate to fire on a knife wielding attacker. When should you shoot? vs When can you shoot? I noticed some misconceptions and that there are many with bad information about the Tueller Drill and what it represents. Always keep in mind that shooting should be a extreme last resort. Shooting is an action that should not be taken lightly and if you have the opportunity to avoid it, avoid shooting if at all possible.

First look at the Tueller Drill. Emphasis on drill. Used routinely today in defensive training.

In 1983 Sergeant Tueller, of the Salt Lake City, Utah Police Department conducted an experiment to determine what a good reactionary gap would be for an officer facing a knife wielding attacker. Through his experiment he found 21 feet to be a good reactionary gap. In the experiment he found that it takes a person, on average, 1.5 seconds to cover 21 feet. It takes the an officer, on average, 1.5 seconds to clear the holster and fire two shots on target. Notice here that these participants in the experiment are not static. In considering that, we can determine the attacker can reach and can stab the officer before or as the officer fires. This indicates a virtual tie. The experiment made it clear that at the distance of 21 feet an officer should have his/her weapon out of the holster and at the ready while giving commands to the possible attacker. The officer should also be prepared to move laterally, off of the line of attack, in response as the attacker moves forward.

The Tueller Drill is NOT a 21 foot rule that justifies a person in firing on a possible attacker. The Tueller Drill is a drill used in defensive training to teach reactionary gap when facing a possible attacker who is wielding a knife, stick, or a improvised weapon that present a danger of serious injury.

If a possible attacker is twenty one feet away from a defender and is not moving forward he/she is not an imminent threat to the defender. Even if a possible attacker has a knife in hand and is verbalizing the threats to do you serious bodily harm he is not an imminent threat due to distance. The possibilities of a knife wielder doing you serious bodily harm at a distance of 21 feet are very low. At 21 feet the knife can not touch you and you are not within the reach of the possible attacker. So, at the distance of 21 feet you are not in imminent danger and should not shoot the knife wielder just because the knife is present and verbal threats have been made.

A defender with a gun has a dilemma. If he shoots too early, he risks being accused of murder. If he waits until the attacker is definitely within striking range so there is no question about motives he risks injury and even death. The Tueller experiments quantified a “danger zone” where an attacker presented a threat and preparations should be made by the defender to respond.


What should a defender be doing at 21 feet?

When facing a possible attacker wielding a knife (or even a stick) you should have your gun out of the holster and at the compressed ready. Prepared to use the gun if necessary and circumstance change forcing the use of deadly force. This is the time for giving commands to the individual to get away and leave the area. This is also the time for you to attempt to make more distance and leave if possible. Avoid shooting if at all possible and get yourself out of the situation without having to use deadly force. With your gun at the ready and preparations made, at the instant the possible attacker begins aggressive forward movement to follow through with the attack you will be more justified to shoot than you would if the possible attacker is stationary and not moving forward to close distance on you. With your gun at the compressed ready you reduce the time it will take to respond to the attack than the time it would take to present from a concealed holster. Even if you are not required to shoot the bad guy, make the call. Call law enforcement and report the incident. Be a good witness and have a good description and a direction of travel. Let law enforcement do their job and track the individual down for prosecution.