Too close – don’t underestimate the knife
The 21-foot rule was developed by Lt. John Tueller, a firearms instructor with the Salt Lake City Police Department. Back in 1983, Tueller set up a drill where he placed a “suspect” armed with an edged weapon 20 or so feet away from an officer with a holstered sidearm. He then directed the armed suspect to run toward the officer in attack mode. The training objective was to determine whether the officer could draw and accurately fire upon the assailant before the suspect stabbed him.
After repeating the drill numerous times, Tueller—who is now retired—wrote an article saying it was entirely possible for a suspect armed with an edged weapon to fatally engage an officer armed with a handgun within a distance of 21 feet. The so-called “21-Foot Rule” was born and soon spread throughout the law enforcement community.