An article published on Police1.com reports research that confirms 21 feet is not necessarily the magic distance to successfully ward off every deadly threat and that more distance could be more apparently required. While this article contains useful information, it unfortunately includes mischaracterizations that need clarification.
First, it erroneously begins: The 21-foot rule has been a topic of conversation in law enforcement since the 1980s when Salt Lake City Police Department Lieutenant Dennis Tueller developed a training drill for his fellow officers. But it is NOT a “rule” and should never be considered a “rule.” It is a training drill intended to be used as a general standard in practice to hone defensive skills.
Second, it states: In this drill, an officer played the role of a suspect with an edged weapon who would charge another officer who was standing about 21 feet away with a holstered weapon. Properly understood, The Tueller Drill does NOT restrict the threat to only an edged weapon.
Appearing in the March 1983 issue of SWAT magazine, How Close Is Too Close? by Dennis Tueller is the original article credited with first establishing the importance of maintaining a “reactionary gap” in defensive force incidents. It begins with the very clear threat scenario description: The “good guy” with the gun against the “bad guy” with the knife (or machete, axe, club, tire-iron, etc.). You’ll notice police trainer Lt. Tueller did NOT limit the threat to only knives or other edged weapons; he included ANY striking weapon (“club, tire-iron, etc.”) used in a person’s hand that is capable of causing death or great bodily harm. The original article illustration itself shows the threat using a club, not a knife.