The Dangers of the 21-Foot Rule

By Dave Dolbee published on in Concealed Carry, General, Safety and Training

The word “rule” has been carelessly tossed about by law enforcement and CCW trainers for decades—perhaps it was just misunderstood. In truth, when talking about the 21-foot rule, most are referring to the “Tueller Drill.” Careless lips have led to some dangerous conclusions, especially among the civilian population. It’s a confusion that’s being cynically exploited to get headlines, and it has even reared its ugly head in the courtroom a time or two, but it needs to be addressed for safety.

Police Officer aiming a Glock pistol with a red barn in the background

Teuller’s drill is well suited to law enforcement and civilians, but the 21-Foot Rule is not.

What Is the 21-Foot Rule?

My first introduction to this topic came about 25 years ago while attending the sheriff’s academy. I remember the class and, more important, the video “Surviving Edged Weapons.” The video and instructional seminars were based on research by Salt Lake City trainer Dennis Tueller. The “21-Foot Rule” was a measure of distance that related to the time it would take an officer to recognize a threat, draw a sidearm, and fire two rounds center mass against an attacker charging with a knife or other stabbing weapon.

To be clear, this article is not intended to be the rule or guide to law enforcement. In fact, most of what this article covers will be common knowledge to today’s LEOs. However, I would hope those with experience behind the badge will chime in and challenge or correct the assertions I scribe here by supplementing it with their own experiences. The ultimate purpose is to give some real-world guidance to the nonprofessional concealed gun handlers reading The Shooter’s Log.


The first issue I have with the 21-Foot Rule is the belief that it is somehow rooted in police doctrine or a legal standard. Removing the number “21” and the word “rule” would go a long way toward dispelling the myth. Tueller’s research did not culminate in a rule; you are not suddenly safer at 22 feet than you were at 20. It is important to distinguish that Tueller developed a drill, not a standard.

Shooter behind cover

Movement and the use of cover is your best defense against any attacker. The is doubly true of an attacker with an edged weapon.

Just as many firearm enthusiasts insist the distinction between a modern sporting rifle and an assault rifle, magazine versus a clip, and a dozen other examples we could come up with off the top of our heads. I believe we need to properly identify our subject as the Tueller Drill and not the 21-Foot Rule. This is not only factually true, it goes a long way toward setting the correct mindset of the neophyte gun handler.

There were two main conclusions that can be contributed to Tueller’s research. First, an attacker with a knife could cover 21 feet in about 1.5 seconds. (This is not word for word, but it covers the general gist.) Second, a helluva lot of law enforcement would be lucky to recognize a threat, unholster their sidearm, and successfully stop the threat from being able to deliver a blow with a knife in less than 1.5 seconds. This was quite a revelation at the time and created much discussion.


Tueller’s lesson should not indicate that anyone, even if they have a knife in hand, is a justified bullet sponge. How many of us carry a pocketknife? Every waitress or busboy in a restaurant would have a target on their chest. Not even in the context of a heated confrontation could you immediately jump to this conclusion. The lesson does not teach that we should shoot a hostile actor with a knife if they are within 21 feet. The lesson merely put a number to the test data and created a mindset for officers to rethink their response and posture to a threat or potentially sudden dynamic attack.

The mindset was fine, but the lessons that followed…not so much. Tueller’s research revealed training deficiencies of the day. As previously stated, it created a lot of discussion, which was good. Where it went wrong, in my opinion, was when they started teaching the number over the mindset. I recall this being demonstrated on the range at the academy. A large, intimidating deputy with a rubber knife rushed a student from 21 feet. The deputy did not run, just marched at a quick pace wielding the knife over his head and screaming obscenities.

Bob Campbell shooting a 1911 pistol from a retention position

Seldom in an emergency situation where you have to draw and fire quickly will you ever see the gun’s sights.

The student had to recognize the threat’s approach, unsnap his holster, and draw his weapon. He failed. In fact, the truth be told, we all failed. Some may have cleared leather and pulled the trigger, but the threat was so close he still would have struck a blow falling on you. Let’s not forget the audience here. You are likely carrying concealed, not openly in a Sam Brown.

The 21-Foot Lesson was—graphically—received. Unfortunately, at the time, we learned the number more than the correct lesson. In time, however, we learned to get off the “X” instead of being a static target. Instead of backing up in a straight line, we were taught to react by moving “off-line.” (Attackers in these scenarios may be so enraged they continue on the beeline path instead of tracking you.) More important, we were taught to read body language, situational awareness (which directions could you move off-line, soft and hard cover, etc.), reactionary gaps, and other close-quarters defensive techniques not involving a firearm.

Final Thoughts

The focus of The Shooter’s Log does not include training civilians to be cops or instruction in matters of law enforcement. However, I see far too many videos of self-professed firearm trainers, tactical weapons specialists, home defense “experts,” and even a few prior LEOs who teach like they did to officers or cadets at the academy or in the military and not to civilians. Sadly, I would say while I respect the effort, they have no business standing in front of a student. Too often, I have heard friends (after such training, watching a cop show on TV, or reading something on the Internet) throw out the term “21-Foot Rule”  and improperly state it as a threshold of safe versus justifiable homicide.

I hope, after reading this and the comments from readers with much more knowledge and experience than I have, that you dedicate some of your concealed carry training to going beyond the minimum gun-handling skills and—as important—practicing your communication skills, situational awareness, and good old-fashioned common sense.

What is your impression of the 21-Foot Rule? Have you ever heard of the Tueller Drill? Have you practiced it? Share your answers, opinions, or experiences in the comment section.


Growing up in Pennsylvania’s game-rich Allegany region, Dave Dolbee was introduced to whitetail hunting at a young age. At age 19 he bought his first bow while serving in the U.S. Navy, and began bowhunting after returning from Operation Desert Shield/Desert Storm. Dave was a sponsored Pro Staff Shooter for several top archery companies during the 1990s and an Olympic hopeful holding up to 16 archery records at one point. During Dave’s writing career, he has written for several smaller publications as well as many major content providers such as Guns & Ammo, Shooting Times, Outdoor Life, Petersen’s Hunting, Rifle Shooter, Petersen’s Bowhunting, Bowhunter, Game & Fish magazines, Handguns, F.O.P Fraternal Order of Police, Archery Business, SHOT Business,, and others. Dave is currently a staff writer for Cheaper Than Dirt!

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Comments (77)

  • Tom


    Much ado about nothing. I’ve heard the “rule” for years and seen it demonstrated in training classes more than once, maybe as far back as academy, 30+ years ago. I never heard it taught as an actual “rule” but as a demonstration to increase awareness. I really doubt many would misinterpret it as a hard and fast rule. But I understand that you’re a writer and need material so it’s OK.


    • Jason


      Actually, in the State of North Carolina, where I received my original CCL training, the “21 Foot Rule” is used to determine justified lethal force. It is taught that an attacker can cover that distance in an extremely short period of time and this limitation does not offer the attacked enough time/distance to evade or seek an alternate position; therefore, stand and fight. This is the reasoning used for the 3 & 7 yard qualification standard, as instructed in class.

      This is the stupidest standard for justification. As the author rightly states, how can a normal carrying civilian, much less a trained officer, identify, draw, confirm threat, determine hazards beyond the threat, aim and pull trigger in under 1.5 seconds much less 5 seconds! But this is the standard taught in North Carolina conceal carrying training.


  • Bob Campbell


    Speaking as someone with a knife scar not inflicted by myself– well done.

    The gun is never the only answer and too often it is found too easy to shoot instead. Your own edged weapon is sometimes a better choice and may be the only choice when the attacker is on top of you–


  • CapChaos


    in our advanced training class “awareness” was based on the “bubble” our example was based on 36 feet around you for scanning. the distance is not set in stone, it’s more about training oneself to be aware as to what is around you at all times…being vigilant is the best defense, you might want to “exit stage left”


  • Doug


    As a confessed stickler for distinguishing between assault weapon and MSR, I appreciate this article very much. Particularly; “The lesson merely put a number to the test data and created a mindset for officers to rethink their response and posture to a threat or potentially sudden dynamic attack.” I see and hear too many people who take “advice” as the word of God and looking for black and white answers to dynamic questions. The key word being dynamic. All of life is dynamic and has to be interpreted in context. One of the worst is the cyber-commando’s phrase “that will get you killed on the street”. No it won’t, because of a million and a half other things. The Tueller Lesson is what’s important. The drill only helps people actualize the lesson.


  • Bob


    I too was taught through “21 foot rule”, 26 years ago in the police academy. But I was also taught it 10 years earlier, by one of my karate instructors. I don’t remember anyone named Tueller, but I remember Dan Inosanto demonstrating in the video. 21 feet was a demonstrated reference point, not an absolute.


  • gwdean


    I remember the days when an officer would get out of his car, with his clipboard in his hand, when responding to a “routine” citizens complaint. Normally leaving his baton in the vehicle–such a bother.

    This lackadaisical approach always bothered me. On a possible gun, or weapon call, they’d leave the best weapon at hand, their shotgun, in the vehicle.

    While you can never foresee every eventuality, especially being ambushed or beset, out of the blue, by an armed citizen; keeping your mind in the game, anticipating and having a plan is always, always, a critical part of an officers duty to himself, his employers and his family.

    While I would do anything reasonably possibly to avoid shooting a person with an edged weapon, if they advanced aggressively towards me, in a menacing manner, or continue to approach after a warning, I’d not hesitate to send two to center mass and one to the head, providing innocents were not endangered.

    I came within 1/4″ of having my aorta punctured many years ago, lung liver and diaphragm damaged & spent a month in the hospital. I don’t recommend anyone ever let someone cut them.


  • Dennis Novak


    One of the problems with the “21 foot rule” is the number 21. The original statement was 7 yards. It has a level of precision (if you can apply that term to a guestimate) of a yard. So a 24 foot rule would be about as accurate. Or maybe we should call it the 252 inch rule.

    It’s a guestimate not a rule. The point is to improve your situational awareness.


  • bill


    The “21-foot rule” should be taught as mindset and situational awareness. The Tueller Drill is an eye opener as most people would not have believed someone could close that distance before they could react! This should ,instead of rote memorization, make folks more aware of what’s going on around them and focus on surrounding people’s “tells”.


    • Bob


      “…… taught as a mindset and situational awareness”. Absolutely perfect way to describe the value of this level of training. I was exposed to this about 30 years I think and have never forgotten. It was a great example on just how quickly a situation can change, so your mindset is that your situational awareness skills are never not working – bad things can and do happen!


  • Matt Santos


    I enjoyed reading this article – especially since it reinforces something I’ve encountered all my life. I attended a number of training sessions in the Army and my professional career (none of which were law-enforcement), and found that the “good” or “correct” idea at the center of the training, was corrupted somewhere along the way, and tended to emphasize the “wrong” things – even to the point of negated the purpose of the training.
    If I understand the point of this article, the drill or rule, was not to dictate a particular action (run, shot, etc.), but to alert the officer that the time for thinking about the situation is over, it is now time to take action (hopefully the appropriate action).


  • Cam Beauchemin


    Good corrective and explanatory article re: 21′ Rule. It is very educational to say the least. The misinformation about this is wide spread. I have seen a segment on TV’s Guns & Ammo, the Handguns portion when they play out the 21′ Rule using a mechanized dummy attaching the law abiding citizen in the scenario where they make it work that the citizen gets 2 shot off within the 21′ distance. I’ve seen this more than once with re-runs of Guns and Ammo being shown. The program director should be requested to ditch this particular show. Thanks.


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