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)

  • praack


    to show the problem with using distance to define the drill look at the recent incidents in the UK, the police there are trained for people with knives yet with the terrorist none were able to avoid or disarm the threat.

    the drill should evolve now into working on technique- moving the student past the “oh crap” phase into the area where they can disarm the threat- trying to get the firearm out – on target and pull the trigger- may not be the quickest solution.


  • Frank


    At the young age of 74 I think a 50 yard rule is fine for me.


  • Randy


    Several of us met for range time yesterday. The Tueller/time/distance concept was included in the discussion over breakfast. I states that by 20 to 25 feet your hand should at least be on your weapon ready to draw if not out and down, and yes, it depends on the situation. One of the newer guys thought that was to far. The regular guys new what was coming next.

    After we got to the range, and warmed up a bit, since you are not allowed to draw, I had him start in the low ready position. I told him when he saw the target move to put two rounds in the black. Perhaps this wasn’t fair as there was plenty of noise as distraction. With the target starting at seven yards, I hit the recall button. The trolley took a couple of second to return but let’s just say most people, even those who practice normal target shooting, are not used to shooting a target that is moving, let alone one moving at them. They are used to taking time to bring the gun up and to steady before the shot. We did this this several times. He did improve, but he was embarrassed a bit. So was I the first time I tried it. Target shooting is good, but when ever possible try to add something to the standard range shooting to push your limits, safely of course.

    Just like in defensive driving, reaction time is only a part of total time. Situational awareness is critical, practice is important, mental preparation is critical.


  • Weldon Paul


    Hey Dale the 21 foot rule does not exist anymore in law enforcement. They have extended it to 30ft now. Law enforcement instructors are saying that the 21ft rule still does not give adequate time to react in a edge weapon confrontation..


  • Larry Wilson


    Just be prepared and practice with the gun you carry. And remember the golden rule. He who hesitates is the one in the box! It almost has to become habit what you do if you need to.


  • sniper


    The truth is, a bad guy with a knife, at 21 feet, will only need approximately 1.5 seconds to close on you. Your shot needs to be fast and accurate


  • G-Man


    Some of you folks may find it interesting to know that most of our federal law enforcement training on edged weapon attacks is derived from research on knife attacks in Great Britain. For obvious reasons their strict gun laws has made edged weapons one of the prevalent assault and homicide tools of choice over there. This offers us an abundance of information that doesn’t exist here in the U.S.

    In federal law enforcement, defensive tactics trainers dedicate entire blocks of training specifically to the dangers of edged weapons. These federal trainers work in programs that also teach State, Local, and foreign police officers that have previously been indoctrinated by the 21-foot Rule.

    Federal trainers acknowledge Tueller’s drill as a valuable training concept, but do so with an emphasis on eliminating any preconceived notions towards the 21-foot Rule. Instead the focus is on the need for a constant awareness over edged weapons and the deadly consequences of misjudging the “Reactionary Gap”.

    For federal trainers, a disregard for the specific 21-foot Rule is due to information garnered from the U.S. Marine Corps at the turn of the century which revealed that charging enemy combatants were still able to keep coming and still seriously wound our troops with edged weapons even after being fatally wounded by weapons fire from rather long distances.

    Combined this with additional federal law enforcement studies which show a person can move 30 feet in 2 seconds. According to FBI training manuals: “There is sufficient oxygen within the brain to support full, voluntary action for 10 to 15 seconds after the heart has been destroyed.”

    My training states that even after being shot, an individual can continue moving 70 yards. These 10-15 seconds is plenty of time for an attacker to lash out with an edged weapon before dropping. For obvious reasons the 21-foot distance is not accepted by any federal training standards.

    As for personal experience, so far I have been lucky when it comes to edged weapon incidents. Having encountered many a knife, only one ever drew blood. However, that was a female at an airport that had gone off her meds and somehow managed to gain access to the flight line and was wondering around. She was suicidal and just as we approached to subdue her she slit her throat. While the amount of blood made the wound appear to be fatal, fortunately she survived.


    • Joe Rhodes


      Thanks for that. More helpful than the article.


    • Russell McClelland


      What a testament to your (and your cohorts) professionalism G-Man as you didn’t presume the suicidal woman in your last sentence was a goner and saved her life.


  • J-trigger


    My Grandpa was a gunsmith so I learned safety early and fired my first shot by age 3. Over 4 decades of shooting I have heard of, and practiced the Tueller drill. I was called to help my best friend get out of a bad situation and My wife was with me 2 friends there and he was supposed to be gone. I stepped out the door with a box to see 4 horrified people backing up and turned to see a large, bare chested boyfriend wielding a large claw hammer, another man with a hand I couldn’t see, and a third with no weapons. 5 lives potentially at risk and 7 rounds on my Glock 36. I wasn’t worried about the assailants(potential) I drill myself constantly and shoot ambidexterously and can cross draw and rack 1 handed. I dropped the box as they were 20 feet and closing, turned my holster side away from them and backed sideways. The threat was real and closing fast and loud, but the sight of me backing at an angle turned caused an immediate reaction. All three stopped the hammer dropped and I saw six hands and over the silence the words “we don’t want any trouble.” They never turned to come at me the whole time, I had less than 15 feet when they stopped. They never saw my gun, which was carrying its 6+1, and they turned giving apologies to walk back to where they came from, leaving a 10″ kitchen knife “hidden hand” and hammer in the grass not knowing that the CIVILIAN training and lifelong drills that nearly cost them their lives was exactly what saved them. Moral: If you are going to carry, don’t just shoot at silhouettes, practice scenarios until reaction is burned into your brain. If you need to, buy paintball guns and safety gear, hurts like heck but may stop you from killing someone that you don’t need to. Don’t get a permit, get a gun, and shoot it a few times; practice, practice, practice. Once you pull the gun YOU are the armed one and they don’t know if you are legal and likely don’t care. Be prepared, but be knowledgeable and practiced, and buy ammunition that doesn’t exit and hit anyone else. You may change a life without ending it and you might save your own in the process. It’s not speed and numbers etched in stone, and if you aren’t a LEO, or a Combat Veteran, it pays to remember that every situation is different and you don’t want to learn the hard way.


  • MadDog


    A young kid with sprinter speed you might need 30 feet. An old slow guy you might get by with 15 feet. Must take in ALL variables.




    Generally a fine written article UNTIL the ‘bullet sponge’ nonsense comes up. ANYONE brandishing any knife in a heated argument is a threat (the pocket knife example really had nothing to do with the topic). A knife has no business in someone’s hand unless it is being legitimately used. And any size knife can be used, and has been, as a deadly weapon. A potential weapon in a ‘heated’ argument (is there any other kind) should be treated as a threat….period.


    • BR549


      That bullet sponge “nonsense”, as you refer to it, pertained to LEOs failing to assess the situation before they shoot first and ask questions later. I could be a fish cutter on the dock and in the middle of an argument with someone over some petty billing issue. That doesn’t mean I’m intentioning to put his heart alongside a recently filleted Sea Bass. Many people who have to work for a living often use the tool they are holding as a finger extension to make a point.

      I could be a carpenter working in an Italian family business and if you happened to come by as a LEO and couldn’t discern that my brother was too lazy to put his hammer or utility knife down to point at me with his finger instead, I’d be attending his funeral because you failed to read the situation before dragging your own insecurity into it. Just because you had a few emotional loose screws wouldn’t mean that there was justification to make my sister-in-law a widow.

      And yes, there ARE other kinds of arguments. I have argued on a number of occasions with people while I have carried concealed. That doesn’t mean that I ever felt threatened by them. Here’s hoping that if they ever give you a badge, you learn about discernment.


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