The Tueller “Principle”

I cringe every time I hear reference to the “Tueller Rule.”

There is no rule, and there never was.  Rather, there is a demonstrated principle. 

Dennis Tueller, a Seargent on the Salt Lake City Police Department, published an article in SWAT magazine in 1983 explaining the outcomes of force-on-force experiments he conducted. 

The centerpiece of his findings was a simple principle:  an average (not exceptional athlete) man can cover 21 feet and make contact with an opponent in roughly 1.5 seconds.  That’s it.  Simple, yet Tueller’s findings proved very valuable in the formation and refinement of defensive tactics over the decades.

Over the years many practitioners have turned this finding into the “Tueller Rule,” which they claim determines an acceptable distance at which to use force to defend against an individual with a contact weapon, such as a blade or impact tool.  This was never the intention of Tueller’s findings. 

The idea that an adversary with a blade only becomes dangerous if within 21 feet is fraught with peril.  Similarly, just because someone is within that range with a knife in hand does not mean they are a justifiable shoot, if other mitigating factors lesson the threat posed.  There is no rule, but rather a principle that allows for better decision making based on time and distance. 

Interestingly, the 1.5 seconds it takes for the average man to cover 21 feet corresponds to the 1.5 second goal promoted for a draw to first shot as the gold standard.  This also highlights a fallacy within the logic of those who refer to a Tueller rule; according to this thought process, a threat becomes viable once within that matching time frame of the self-defender’s draw.  This is exceptionally dangerous thinking. 

To begin with, what guarantee is there that the draw can be made within that time frame?  Are draws never botched?  Further, counting on a single round from a handgun to stop a charging adversary is asinine.  If the Tueller “rule” guides you to the conclusion that you are justified in drawing a gun only once a knife-armed adversary gets within 21 feet of you, then you are gravely misunderstanding Tueller’s work. 

Tueller did a fine job in demonstrating just how quickly distance can be closed, and the overriding lesson to be learned is that more distance is always better, and seemingly significant distance can be closed very quickly.  A still-ambiguous threat, armed with a contact weapon, should be handled with tactics such as creating more distance, getting behind obstacles, etc…, not by mentally calculating a red line at 21 feet.