The 21-Foot “Rule” Is Back in the News

by | September 25, 2019

Originally published on the Force Science Institute website. Republished here with permission.

Yes. The 21-Foot “Rule” is back in the news. And if we’ve been doing our job as police trainers, most of you will be thinking, “It’s not a rule! It’s simply the principle that an average person can sprint 21 feet in roughly 1.5 seconds. Incidentally, that’s about the same time it takes an officer to draw a firearm and fire two unaimed shots.”

In 1983, police trainer Lt. Dennis Tueller thought this insight might be important for officers who would face suspects armed with edged or blunt weapons. To get the word out, Tueller authored “How CLOSE Is TOO CLOSE?” an article first published in the March 1983 issue of SWAT magazine.

Tueller’s lessons were unequivocal. As soon as you recognize that an armed suspect is close enough to reach you, look for cover, draw your weapon, utilize available barriers, buy time where you can, and even consider tactical withdrawal. Tueller advised officers to give verbal warnings and cautioned that even perfect shots on a charging suspect may not be enough to overcome their forward momentum.

Tueller conceded that, despite an officer’s best efforts, firearms may be needed to stop sudden, close quarter, armed attacks. But a fair reading of Tueller’s work would never result in the belief that officers could simply shoot anyone they perceived as being armed and within 21 feet. Or that officers were presumptively safe from anyone outside of 21 feet.

Gordon Graham: Law Enforcement Officers and the 21-Foot Rule


Nevertheless, the 21-Foot Principle came under scrutiny as critics sidestepped Tueller’s published work, and instead offered anecdotes as evidence that “some” officers believed they could use deadly force based solely on an armed suspect standing closer than 21 feet. Some reform advocates went so far as to suggest this unreasonable approach reflected the “culture” of policing.

Anyone taking an unbiased look at the police profession knows that American police resolve the overwhelming majority of deadly force encounters without firing a shot. Even now many of you are remembering the times you could have lawfully used force, even deadly force, but instead generated voluntary compliance. That said, in the wake of high-profile distortions, leaders in our profession thought it wise to reinforce the premise of Tueller’s work.

In 2014, Dr. Ron Martinelli authored Revisiting the “21-Foot Rule,” wherein he rejected any suggestion that a suspect merely possessing a knife at less than 21 feet could be summarily killed. Martinelli too had heard the 21-Foot “Rule” being misstated by experts on all sides. He challenged any oversimplification of Tueller’s work and, citing Force Science research, argued that to properly assess threats required a sophisticated understanding of perception, decision making, and action.

There are simply no shortcuts to understanding use of force decision making. It requires a sophisticated understanding of laws, policies, tactics, and human factors.

Calibre Press, one of the most influential public safety training companies, made clear in Street Survival II (2018) that, “No one should ever think, or certainly ever teach and endorse, a policy that says anyone within 21 feet of you, armed with an edged weapon, should be shot!”

And, in Chief Ken Wallentine’s video The 21-Foot Principle Clarified (2018), Dennis Tueller himself confirmed he never taught that an officer could shoot anyone with an edged or impact weapon simply for being closer than 21 feet from the officer.

If any individual within the profession ever held a different understanding of the 21-Foot Principle, the efforts of these leaders should ensure the “culture” of policing never does.

Back in the News

So, with the culture of policing intact, how has the 21-Foot “Rule” found its way back into the news?

Let’s start with Buchanan v. City of San Jose. Officers responded to an emergency call that a man was threatening a family with a knife. Sadly, it turned out that the man had actually called the police on himself with the intent of committing “suicide by cop.” When officers arrived, they saw a man armed with a knife who then advanced toward them “in a threatening manner.”

Starting from a distance over 130 feet, the man first walked toward the officers and then accelerated into a “trot,” which was described as a “fast” and “rapid” pace. Still armed with a knife, the man ignored repeated commands to stop. When the athletic suspect reached approximately 55 feet from the officers, they opened fire. The suspect travelled another 37 feet toward the officers before falling.

Here’s where we pause to let that last fact sink in.

As the judges in Buchanan scrutinized the officers’ conduct, one judge curiously pointed to the police department’s policy and argued, “, a person armed with a dangerous weapon, such as a knife or bat, constitutes a danger to the safety of the officer when that person is at a distance of 21 feet or less from the officer. Thus, under the Department’s own 21-foot rule, , at a distance of 55 feet, presumptively did not pose an immediate threat to the safety of the officer when he was shot” (emphasis added).

With sincere respect for the judge, a former United States Marine and Harvard Law School graduate, there is an obvious flaw in his logic. Even after the officers engaged the armed suspect in Buchanan, he was able to travel another 37 feet. That fact alone should have dispelled any presumption that armed, attacking suspects beyond 21 feet do not pose an immediate threat to the safety of officers.

Thankfully, the majority of judges in the Buchanan case disagreed with the lone dissent and expressly noted, “The 21-foot rule provides that a person at a distance of 21 feet or less may pose a threat to the safety of an officer. It does not follow from this rule, or any other, that armed suspects never pose a threat beyond 21 feet.” With that observation, the Buchanan court upheld the lower court’s grant of summary judgment on behalf of the officers. But if you pay attention, they did more than that.

Buchanan was an appeal from a lower court’s summary judgment based on qualified immunity for the officers. Readers familiar with qualified immunity understand that the rule protects officers from civil liability for official conduct. To protect officers, who must make multiple judgment calls each day, the law makes it hard to win a lawsuit against the police.

If there can be honest debate among officers as to whether a use of force was reasonable, then qualified immunity applies. However, the court can deny this protection if it would have been obvious to any reasonable officer that the police violated a constitutional right.

Frequently, at the summary judgment stage, courts will simply uphold qualified immunity by deciding that it would not have been obvious to a reasonable officer that the suspect’s constitutional rights were violated. The Buchanan court went one step further and expressly held that, under these circumstances, the immediate threat to the officers justified their use of deadly force. This is the courts way of saying, this wasn’t a close call.

The Buchanan case highlights the need to have knowledgeable attorneys and human factors experts participating at all stages of investigation and case preparation

The Buchanan case highlights the need to have knowledgeable attorneys and human factors experts participating at all stages of investigation and case preparation. But as this next case shows, not all attorneys or use of force experts understand (or want to understand?) the nuances of the 21-Foot Principle.

Florida v. Michael Drejka

Some of you are familiar with the case of Florida v. Michael Drejka, or at least have seen the video. Drejka was dubbed the “handicap parking spot shooter” after he verbally confronted a woman for parking in a handicap parking space. When the woman’s boyfriend unexpectedly pushed Drejka to the ground, Drejka (still on the ground) drew his pistol and shot the boyfriend who stood several feet away. He was ultimately charged and convicted of manslaughter and now awaits sentencing.

The legal aspects of the Drejka case were analyzed in detail by Andrew Branca, author of The Law of Self-Defense. Branca covered the case in an online article, “Drejka Case Analysis: When the ‘Tueller Drill’ 21-Foot Defense Is Defined Out of Existence.”

Branca is a veteran legal analyst who begins his critical assessment with an important disclaimer: “My problem with this outcome has nothing to do with the fact the Michael Drejka was found guilty—maybe he was guilty.” Instead, Branca took issue with the attorneys’ and use-of-force experts’ treatment of the 21-Foot Rule. As well he should have.

As mentioned above, the central point of Tueller’s 21-Foot Principle is the awareness that an average person can sprint 21 feet in roughly 1.5 seconds. When deciding how to respond to a lethal threat, the time it takes to draw from a holster and fire two unaimed shots becomes important. But the means of attack doesn’t change that if an assault is launched from 21 feet, you have about 1.5 seconds to respond.

So how did the prosecution in Drejka explain the 21-Foot Rule? Through their expert witness, the prosecution told the jury that the 21-Foot Rule didn’t apply unless three components were met. First, a law enforcement officer with a holstered weapon must be involved. Second, the suspect must be advancing on the officer. And third, the suspect must have an edged weapon. According to the prosecution, unless you have all three, the 21-Foot Rule doesn’t apply.

Andrew Branca does an outstanding job dismantling what most of us by now should recognize as an unreasonably narrow description of the 21-Foot Rule. His critique of the prosecution, the defense and the experts’ handling of the Drejka case is well worth reading.

“The Tueller Drill” Was a Starting Point

If we learn anything from the Buchanan and Drejka cases, it’s that human factors research and education is still critically important. The Tueller drill itself was merely a starting point for important situational awareness. Consider that Force Science studies (see links below) have documented the ability of subjects to sprint and perform a slash in 1.5 seconds from distances closer to 30 feet!

Even so, the factors that influence real-world threat assessments and response can’t be reduced to simple math problems.

While it’s important to know, for example, that a suicidal person holding a gun to their head can push the weapon in your direction, point and shoot in about 1 second, that fact alone does not justify pre-emptively shooting an armed suicidal person.

There are simply no shortcuts to understanding use of force decision making. It requires a sophisticated understanding of laws, policies, tactics, and human factors.

Force Science students will remember that to apply a “simple” reaction distance principle (like the 21-Foot “Rule”) requires the consideration of such factors as pre-attack indicators, emotional arousal indicators, attention and perception influences, speed of assaults, firearms accuracy, action and reaction times, start and stop times, sprint speeds, the effect of uniform weight on performance, and decision making processes. Not to mention, the effect of heightened emotional and physical stress on all of these factors!

It’s inevitable that the foundation of the 21-Foot Principle will remain an important part of your training development and use of force case reviews. I encourage readers to use their tape measures sparingly and avoid any temptation to oversimplify or narrowly define any police practice. Instead, continue to apply human factors research and lessons from cases like Buchanan and Drejka for the next time the 21-Foot Principle is back in the news.

See the following Force Science News articles for related coverage.

New Sprint Study: Are You Prepared for This Offender Speed?

Is The 21-Foot Rule Still Valid When Dealing with An Edged Weapon? (Part 1)

Is the 21-Foot Rule Still Valid When Dealing with an Edged Weapon? (Part 2)


  1. The Buchanan case was the subject of The Calibre Report: New Knife-Attack Decision. I encourage readers to read this excellent summary, analysis and additional lessons learned.
  2. Because a witness testified that the suspect had stopped at some point before reaching the officers, the dissent was not willing to credit that the suspect was advancing throughout the encounter. Although this witness’ testimony was contradicted by her prior testimony, the dissent argued that it nevertheless created a genuine issue of material fact that should only be resolved by a jury. The majority rejected this argument in part because the witness was unable to describe what the suspect did after he reportedly stopped, while other witnesses testified that the suspect continued to advance on the officers.

Lewis “Von” Kliem, MCJ, JD, LL.M., has nearly 30 years in the criminal justice profession and has worked as a civilian police officer, attorney, educator, and author. A former attorney with Lexipol, Von is the executive editor of the Force Science News, and is co-owner of Von Kliem Consulting, LLC, where he trains and consults on constitutional policing, use of force analysis, crisis communications, and trauma-informed interviewing. About the Force Science Institute The Force Science Institute (FSI) is comprised of a team of physicians, lawyers, psychologists, scientists, police trainers and law enforcement subject matter experts dedicated to the advancement of knowledge and training in criminal justice matters. FSI conducts sophisticated scientific research studies into human behavior documenting the physical and mental dynamics associated with the societal demands of the peace-keeping function, including high-pressure situations and use-of-force incidents. Its findings apply to citizen-involved uses of force as well as impacting investigations of officer-involved force applications. FSI research, when applied to training, enhances officer performance and public safety.

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