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)

  • Peter


    This is a great article about what the Tueller drill is and is not. Thank you.

    I wanted to share the following link to a YouTube video. I think it is one of the better demonstrations of off-angle movement and its effect on the principles of the Tueller drill. It is, I believe, an excellent complement to the discussion in this article.

    Instructor Zero and Doug Marcaida talk a lot at the beginning, I think what they are saying is good, but if you want to “cut to the chase,” go to 4:30.

    After seeing this video, you should be convinced that there is far more to training for successful armed defense than simply putting lots of bullets into a paper target downrange.


  • fred


    The ’21 ft rule’ test apparently relies on surprise by the attacker. Makes sense that a surprise attacker has a great advantage suddenly charging and stabbing you. However, it would be informative if the 21 ft rule was tested when the attack was against an armed person who was on alert and on guard against a sudden attack. What if the officer was on guard with his firearm in hand and ready to fire?


  • Chad Ridler


    As a Former Use of Force Trainer and retired Martial Arts Instructor, yes I have known about the “21 foot rule” for a long time…however I’ve always encountered it’s use a little differently. Not that you are “safe” at 22 feet, but for an LE officer it meant a guy with a knife means you better have your firearm (at the very least) at low ready.
    The drills I’ve seen have all been pointless since the student always knew that the pretend bad guy infront of them had a knife and was about to use it so they had an advantage they wouldn’t have had in a real confrontation.
    We always used this ‘rule” simply to engrain situational awareness and just like any Martial Art, it teaches the different ranges.. such as kicking/punching/grappling.
    To contrast this “rule”, when we would teach our knife classes, one of the major tenants is to never advertise the fact that you have a knife in your hand.


  • Dale


    Though I’ve never heard of the 21 foot “rule” I’ve often wondered how quickly I could react to an imminent threat to me or my family.

    After reading your article, I’m even more concerned as I feel it would take me a lot longer to recognize that I am in imminent danger, then begin the reaction to draw a concealed carry weapon, quick-check for friendlies in the area, then fire. I’m not military or law enforcement trained (other than an M-16 many, many moons ago) and am quite sure it would take me a bit of time to go through the steps.

    That being the case it appears to me that if someone is brandishing a knife or other serious instrument, I would need a much longer time. I’m not even sure 50 ft would be enough.

    Is anyone aware of actual studies of lay people such as myself? Or, in the alternative, am I just kidding myself about CCW and its benefits to me


    • Firewagon


      Although I played the Green Machine game for 20 years, we were never taught anything about this drill or 21 foot rule. Of course, “we traveled not often ALONE!” Once aware of this ‘person of average physicality’ having the ability to be on you in +-1.5 seconds, I trained to get those two shots off in under 2 seconds from concealment – rarely, however, being able to break the second shot under 1.5sec! Some, like Jerry Miculek, can git-er-dun in <1 sec; however, have not seen it done from concealment. My issue with the 'whole idea' of this rule, has to do with the fact some whack is NOT going to be coming at you in any 'direct' manner, especially if they have the intention of doing you some harm/assault/robbery! They want to 'suddenly' appear at your elbow, or already have you looking up from the ground, if still conscious. Consider the recent NO assault: My hated phrase, bottom line reads, if you have the time to see "it" coming, as noted, definitely MOVE, learn to access your smoke pole while moving, and better, have some plan/idea how you might need the ability to FIGHT your way to your gun! As proven in too many instances, police officers are often shot with their own weapons!!




    The above article is absolutely correct. In my Martial Arts experiences persons can move much faster then you think they can and to be prepared for that takes a lot of training and experience to overcome. My best advice is to practice, practice, practice to be prepared. Getting ‘OFF-LINE” is of great value, however again it takes practice, practice, practice to achieve a proficient level to be prepared.


  • Ross Bonny Jr.


    Excellent article. I have seen videos of traiining drills where the ‘assailant’ was 21 feet or even further from the ‘victim’ and by running could easily overwhelm the ‘victim’ before the ‘victim’ could react, let alone present, aim and shoot. Even close quarters shooting technique wouldn’t allow the ‘victim’ to stop the attacker. In my opinion, even 30 feet would be questionable.


  • dprato


    I think this is an excellent article and long overdue. For the civilian population in particular with the variability of personal skills with a firearm and the potential speed differences and skills of an attacker it is wise to put the emphasis not on distance but threat recognition and potential responses to different situations that will keep a person safe. Even with that said and done perhaps the most important thing is whether or not the person being attacked has the will to use their weapon in the first place.


  • DaveW


    An officer should always be “situationally aware”. The movements of a subject should be observed for any change in posture or demeanor. An officer should maintain distance between the subject and the office in order to mitigate the possibility of being grabbed/assaulted.

    The subject who decides to act will have the element of surprise since the subject knows they are going to act before the officer can detect intend and react to that intent. The same as driving. The drive ahead decides to panic stop. The driver following has to see the brake lights come on visually, recognize what is happening, transmit the information to the foot to push on the brake. This is why we have the car length rule for following. (Naturally this has zero meaning for anyone who has driven in LA.)

    The officer should, if the subject is advancing, be backing away while drawing the sidearm or baton (if issued). If time is not sufficient, it may be best to fall backward while drawing and firing.


  • art


    took the info to mean if an attacker has a knife and is threatening you get you gun out and be ready. i probably have no business even giving my thoughts hear just a civilian that started carrying in the late 80’s because of my first death threat.
    even if you can shoot him center mass, if you don’t take out the spine you are probably going to get stabbed. my guess is even a heart shoot won’t stop him in time to keep him from stabbing you. like deer hunting you can shoot one in the heart and he can run 50 to a hundred yards before expiring.
    as you stated keep moving off the X, and keep firing. as he gets really close maybe a head shot.
    hopefully just get your gun out will stop most thinking perps. if it doesn’t keep moving and changing directions. keep firing until he is not moving toward you. hope i never have to play this game for real. just carrying insurance and insurance does not cover everything.
    probably should have just kept my keyboard away. great article!!


  • David S


    Thank you for the article. I was not aware of the “Tueller Rule”. My only knowledge of anything designated by 21 was what was told to one of my concealed carry classes, and the gist of it was that if an incident occurred in which you had to use your weapon it would more than likely be at a distance of 21 ft or less. I understood, but that seemed pretty close to me and I would hope that my situational awareness would afford me the chance to spot, draw, and engage if required. Our course of fire was at 3, 5 and 7 yards and I feel pretty certain the 7 yard target had something to do with the 21 foot history. Myself, while I do practice “short shots”, maintain a pretty good routine of practice from 10-25 yards. Thanks again for the article.


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