Self-Defense: The 21-Foot Principle

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Understanding the relevance of the 21-Foot Principle, often called the 21-Foot Rule, in modern self-defense training.

The 21-Foot Principle, often mistakenly referred to as the “21-Foot Rule,” gained prominence through the work of Dennis Tueller, a police officer with the Salt Lake City Police Department. This principle emerged from Tueller’s informal studies on the potential threat posed by an attacker armed with a knife.

His findings suggested that an able-bodied male could cover approximately 21 feet in a second and a half, which is roughly the same amount of time it takes for a reasonably trained police officer to draw their firearm and discharge a shot. This concept has since become widely known and applied, even within legal circles, despite the misnomer “21-Foot Rule.”

The Origin and Misinterpretation of the 21-Foot Principle

The term “21-Foot Rule” is a bit of a misnomer because it suggests a hard-and-fast rule when, in reality, it’s more of a guideline or principle. Tueller’s research was intended to help officers understand the time frame within which an attacker could become a deadly threat. The crux of the principle is that an attacker could potentially cover 21 feet in the time it takes an officer to draw and fire their weapon. This realization has significant implications for law enforcement and self-defense training, providing a framework for understanding when a threat becomes immediate and unavoidable.

Application and Training

Incorporating the 21-Foot Principle into training helps individuals recognize when they might be in imminent danger. However, it’s essential to understand that the exact distance can vary depending on numerous factors. The principle encourages considering the context of a potential threat, including the attacker’s physical abilities, the presence of obstacles, and whether the attacker is visibly armed.

For example, a knife in-hand is a more immediate threat than a folding knife in a pocket. The “Danger Zone,” as Tueller called it, will also vary based on the skill of the officer or armed citizen. What’s the availability of cover/concealment? What are the avenues for retreat or movement? How quickly can the person draw their firearm? All of these factors, and others, play into the analysis of when an attacker poses a deadly threat.

Legal Considerations and the Totality of Circumstances

When determining the legality of using deadly force, the totality of circumstances is paramount. The actions of the defender are judged based on whether they were reasonable given the immediate threat posed. The challenge lies in the timing: acting too soon might result in a charge for murder, while acting too late could result in serious injury or death. The 21-Foot Principle assists individuals in articulating why they perceive a threat as an immediate threat based on the circumstances, which can be crucial in legal proceedings.

Civilian Vs. Law Enforcement Application

While some argue that the principles applied to law enforcement don’t always extend to non-law enforcement contexts, the core idea remains relevant. In many jurisdictions, if a person is charged with using a knife, the defender might be justified in using deadly force if they can articulate the threat they faced.

The ability to explain why an attacker posed an immediate threat is critical, aligning with Massad Ayoob’s concept of “Can You Articulate” (CYA) the justification for your actions. The CYA theory underscores that it’s not enough to simply act in self-defense. One must also be capable of articulating the reasons for those actions in a clear, logical and legally sound manner. This ability can be crucial in determining the legal outcome of a self-defense incident and protecting oneself from potential legal consequences.

Practical Training and Real-World Application

Hands-on training drills, such as those conducted at Gunsite, Rangemaster, Thunder Ranch, the Firearms Academy of Seattle and other reputable training organizations provide practical insights into the 21-Foot Principle. These drills often involve scenarios where trainees experience firsthand the difficulty of reacting to a fast-moving threat, illustrating how quickly an attacker can close the distance.

The AOJ Triad

Understanding the 21-Foot Principle also involves considering the AOJ triad: Ability, Opportunity and Jeopardy. This framework, often discussed by self-defense expert Ayoob, helps determine the legitimacy of using deadly force.

• Ability: Does the attacker have the means (a weapon, physical strength) to cause harm?
• Opportunity: Is the attacker close enough to use their means effectively?
• Jeopardy: Is there an apparent intent to cause harm, such as verbal threats or aggressive actions?

This triad helps ensure a comprehensive evaluation of the threat, reinforcing the importance of context in making split-second decisions.

Conclusion

The 21-Foot Principle remains a crucial element in defense training, emphasizing the importance of context and rapid response in face-to-face confrontations. While it originated from law enforcement studies, its application extends to non-law enforcement contexts, providing a valuable tool for understanding and articulating the presence of an immediate threat. By considering factors such as the AOJ triad and engaging in practical training exercises, individuals can better prepare themselves for potential encounters and ensure their actions are both reasonable and legally justifiable.

Editor's Note: This article originally appeared in the October 2024 issue of Gun Digest the Magazine.

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