There can be a lot of misunderstanding associated with the “21 Foot Rule.” As such, Dennis Tueller, the creator, sat down to discuss this contested concept with Ken Wallentine of the Utah Attorney General’s Office in a CopTalks episode.
It begins with a discussion on the concept of a reactionary gap and human performance factors. Every person has a reaction time, which can be reduced with heavy training and stress inoculation, but nevertheless, it will always require some time. Dr. Bill Lewinski and other researchers from the Force Science Institute® demonstrated that suspects can draw a gun from their waistband, point and fire in as little as nine-one-hundredths of a second. In comparison, the reacting officer—even with gun drawn and anticipating the need to fire—needs an average of thirty-one-one-hundredths of a second to perceive the threat and pull the trigger.
This research doesn’t include the additional time of recognizing the threat as a threat (rather than something like a cell phone) or the distraction of local stimuli. But what does this have to do with the 21 Foot Rule?
Research initially conducted and published by Dennis Tueller shows that an armed assailant, standing 21 feet from an officer, is able to stab/slice the officer with their edged weapon before the officer is able to understand, react, draw and fire their handgun more than half the time.
However, officers who were able to fire were still very likely to be stabbed/sliced. As a result of this study, officers are repetitively taught to draw their weapons and be prepared to defend themselves well before an assailant closes the 21 foot distance.
There’s a lot more to this conversation, though, which can be seen here: