TLDR: The 21-foot rule comes from a 1983 study by Sergeant Dennis Tueller of the Salt Lake City Police Department, who found that an attacker armed with a knife could cover 21 feet in 1.5 seconds, which is roughly the same time it takes a trained shooter to draw and fire a holstered handgun. It was never meant to be a hard rule. Tueller called it a way to think about reaction time, and the original article was titled “How Close Is Too Close?” New peer-reviewed research from 2020 puts the real reactionary gap closer to 32 feet for almost all officers to draw and fire before being reached. Movement matters too. Sidestepping at 90 degrees dropped the stab rate in that study from 33 percent to just 5 percent. For preppers, survivalists, and anyone planning for SHTF or grid-down scenarios, the 21-foot rule is one of the most important pieces of self-defense knowledge you can carry.
If your plan for civil unrest, martial law, or a long-term EMP attack involves a firearm and a holster, you need to understand this rule before you ever need to use it. The next 1,500 words walk through where it came from, what the science actually says, and how it applies when the rule of law thins out.
Where Does the 21-Foot Rule Come From?
In March 1983, Sergeant Dennis Tueller of the Salt Lake City Police Department published an article in SWAT Magazine titled “How Close Is Too Close?” Tueller, who worked as a police trainer at the time, wanted to answer a question every officer eventually asks. If an attacker with a knife or other contact weapon was charging at you, how far away did the threat need to be before you could draw and fire two accurate shots from a holstered sidearm? He grabbed a stopwatch and timed volunteers running at a target.
What Tueller found was that a typical attacker could cover 21 feet in roughly 1.5 seconds. About the same amount of time it took a trainee to draw and fire two shots. The article was followed by a police training video of the same name, and the concept tore through law enforcement training across the country.
Tueller never called it a rule. He called it a reaction-time concept, and the entire point was to make trainees understand that close is too close. Four decades later, the shorthand “21-foot rule” has stuck, even though Tueller himself probably winces every time someone treats it as gospel.
What is the 21-foot rule in Justified?
If you searched for the 21-foot rule and the word “justified” together, you may have been looking for the FX television show, not a legal question. Season 5, Episode 10 of Justified, titled “Weight,” gives us one of the more memorable 21-foot rule moments on television. Danny Crowe, played by A.J. Buckley, spends most of the season bragging about the 21-foot rule. He explains it to his little brother Kendall. He brings it up to a DEA agent. He treats it like a magic spell that lets a guy with a knife beat a guy with a gun.
In the showdown with Deputy U.S. Marshal Raylan Givens, Danny asks how far apart they are standing. Raylan says about twenty feet. Danny asks if Raylan ever heard of the 21-foot rule. Raylan, dry as ever, says he has not. Danny charges with his knife, makes it about three feet, trips into the hole he had just dug for his dead dog Chelsea, and the blade goes through his own throat. He chokes on his own blood. Raylan stands there, watches it happen, and walks away. It is a great scene, and it is also a pretty good real-world commentary on the rule itself. The 21-foot rule is real. It is also not a guarantee of anything, especially not for a guy who just learned about it from a magazine article and decided to bet his life on it.
Is the 21-Foot Rule Actually Justified as a Concept?
Setting the TV reference aside, the 21-foot rule is justified as a training concept, not as a green light to shoot someone the moment they step inside that distance. The science behind it holds up. An average adult male in decent shape can run 21 feet in about a second and a half. A trained shooter with a retention holster takes roughly the same amount of time to draw and fire. So if an armed assailant could close that distance before you could respond, the threat is real and immediate.
Where it breaks down is when people treat 21 feet as a bright line for lethal force. Even in a SHTF scenario where formal use of force standards may feel less applicable, the moral and practical math still matters. The question is not just how close the attacker was. It is whether they had the ability, opportunity, and intent to do you serious harm, and whether your response was reasonable under the totality of the circumstances. The 21-foot rule informs that analysis. It does not replace it.
How Fast Can Someone Close 21 Feet?
A motivated attacker in average shape can close 21 feet in about 1.5 seconds. Tueller’s original timed volunteers landed in that range, and a 2020 ALERRT study (the Advanced Law Enforcement Rapid Response Training Center) confirmed it. Researchers timed 76 college students sprinting 21 feet and found the average came in right around 1.5 seconds, which lined up almost perfectly with what Tueller measured back in 1983.
Younger and athletic attackers can do it faster. Older or out-of-shape attackers will be slower. Surface conditions, footwear, and surprise all factor in. The number is a useful baseline, not a guarantee. What it really tells you is that a knife can close conversational distance faster than you can react, draw, and fire. That is the lesson worth burning into memory.
Can the Average Person Move 21 Feet in 1.5 Seconds?
Yes. The average person can cover 21 feet in roughly 1.5 seconds at a hard sprint. ALERRT’s data backed this up. So did MythBusters in their 2012 “Duel Dilemmas” episode, where the gun-wielder at 20 feet only managed to fire just as the knife attacker reached him. Inside that distance, the knife always won.
What changes the answer is reaction time. The 1.5 seconds an attacker needs to cover 21 feet starts when they decide to charge. Your 1.5 seconds to draw and fire only starts after your brain registers the threat, decides to respond, and your hands start moving. That perception-to-action gap, often a quarter to half a second on its own, is the part most people forget when they do the math. By the time your firearm clears the holster, the attacker is closer than 21 feet.
Why Is the 21-Foot Rule Important?
Understanding the 21-foot rule matters because it forces you to think about distance and time the way they actually behave under stress. Most people, including a lot of trained shooters, dramatically underestimate how fast someone can cover ground. They think they have time. They do not. Walking through the Tueller drill on a range, even once, recalibrates your sense of personal space permanently.
Why It Matters Even More in SHTF and Grid-Down Scenarios
If you are reading PatriotPowerLine, you are probably already thinking past the everyday parking lot mugging. In a grid-down or martial law scenario, the dynamics shift. Police response goes from minutes to never. The people willing to cross 21 feet at you with a contact weapon multiply. Drug-addled looters, desperate strangers, and small groups working together do not respect personal space, and they do not stop because you yelled at them.
In a long-term civil unrest situation, you are also more likely to be approached by people pretending to need help. The closer they get before they show their hand, the less the 21-foot rule helps you. After an EMP attack or any extended grid-down event, your security posture has to assume that anyone inside that range is a potential threat until proven otherwise. That sounds harsh. It is also how people stay alive when the rules thin out.
The Mindset Shift
The deeper value of the 21-foot rule is that it pushes you to stop fixating on the firearm as your only answer. You start paying attention to your surroundings. You watch the hands. You create distance before things go bad. Distance equals time, and time equals options. Inside 21 feet, your options collapse fast. The prepper who internalizes this is the one who avoids the fight in the first place.
The Reactionary Gap: What 21 Feet Actually Buys You
The reactionary gap is the distance you need between yourself and a potential threat to perceive, decide, and act. Twenty-one feet, or seven yards, is the most cited number, but it is not magic. Self-defense instructors talk about 21 feet because it lines up with the original Tueller drill data and because it is roughly the length of a small living room or a parking space and a half.
What 21 feet actually buys you is one chance to draw and fire if everything goes right. Holster works smoothly. Hands cooperate. You see the threat develop the moment it develops. Your sidearm comes out clean. You hit a human silhouette under stress. Anything goes wrong and the danger zone collapses on you. The reactionary gap is not safety. It is the bare minimum of working room.
New Research: Why 21 Feet Might Actually Be 32
A 2020 peer-reviewed study from Sandel, Martaindale, and Blair, published in Police Practice and Research, took the Tueller concept into the lab. They ran four studies. They timed 76 students sprinting 21 feet and confirmed the 1.5-second figure. Then they tested 152 police officers drawing and firing one round at a human silhouette. The average draw and fire time was 1.80 seconds. The median was 1.73 seconds. Times ranged from 1.03 seconds to 3.40 seconds. Only 86 percent of those officers actually hit the target.
In the third study, they had 57 officers face a charging suspect with a shock knife in a realistic training environment. Twelve percent of those officers were completely unable to draw and fire before being reached. They could not get past their retention holster in time. The researchers concluded that for 95 percent of officers to be able to fire before a random suspect closed the distance, the gap would need to be about 32 feet, not 21.
The fourth study tested movement. When officers stood still, suspects successfully stabbed them 33 percent of the time. Sidestepping at 90 degrees dropped that rate to 5 percent. Back-pedaling brought it to 8 percent. Stepping at 45 degrees toward the attacker came in at 26 percent. The takeaway is brutal and useful. Movement keeps you alive. Standing still and trying to outdraw a charging attacker is a coin flip you do not want to call.
How to Run the Tueller Drill at Home or at the Range
The Tueller drill is the most valuable training exercise you can run if you carry a firearm for self-defense. The simplest version puts the shooter and a partner back to back, separated by a target 21 feet in front of the shooter. On a signal, the partner sprints away, and the shooter draws and fires at the target. If the shooter hits and the runner did not cover 21 feet before the shot fired, the shooter “wins.”
A more stressful version puts the partner 21 feet behind the shooter, charging forward. The shooter has to draw and fire at the target before getting tapped on the back. This version drives home what reaction time actually feels like, not what it looks like on a stopwatch.
A full-contact version uses a training replica gun and lets the shooter practice sidestepping while drawing. This is the variant the ALERRT research showed actually works. If your range allows it and you have a partner you trust, run it. If you have property and dry-fire-only training in mind, set up a timer and a static target and run the back-to-back version. Continue to practice. Skill perishes faster than ammo.
Where the Rule Fits in Your Self-Defense Stack
The 21-foot rule is one piece of a larger self-defense framework. It works alongside situational awareness, hardened doors and entry points, layered defense, and the willingness to retreat when retreat is still an option. For preppers planning for SHTF or martial law conditions, it pairs directly with perimeter awareness, communication plans with family or group members, and the discipline to use deadly force only when nothing else will incapacitate the threat.
If you carry a firearm as your means for self-defense, your stack should also include training in the legal side of use of force, a quality holster you can draw from under stress, and a dry-fire routine. Knowing the science of the 21-foot rule is step one. Knowing the law where you live, even in a scenario where law enforcement is degraded, is step two. Both still matter.
The Bottom Line on 21 Feet
The 21-foot rule started as one cop with a stopwatch trying to teach his trainees what close really means. Forty years later, the concept holds up, the number has been refined, and the principle is still the most important distance lesson in self-defense and survivalist circles.
Worth burning into memory:
- The 21-foot rule comes from Sergeant Dennis Tueller of the Salt Lake City Police Department, published in SWAT Magazine in 1983.
- An average attacker can cover 21 feet in about 1.5 seconds. A trained shooter needs 1.5 to 1.8 seconds to draw and fire two shots from a holster.
- The original article was titled “How Close Is Too Close?” and was framed as a reaction-time concept, not a hard rule.
- 2020 peer-reviewed research suggests the safe reactionary gap is closer to 32 feet for almost all shooters to draw and fire successfully.
- Movement saves lives. Sidestepping at 90 degrees dropped the stab rate from 33 percent to 5 percent in the ALERRT study.
- Inside 21 feet, distance equals time, and your options collapse fast.
- In a SHTF, grid-down, civil unrest, or martial law scenario, the 21-foot rule matters more, not less.
- Continue to practice the Tueller drill on the range, and run it with movement built in. Standing still in a real fight is the slowest way to lose one.
The honest version of the 21-foot rule is shorter than the legend. Close is close. Train like you mean it, and build the rest of your prep around the same principle.
