Tueller Drill

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The Tueller Drill is a situational awareness and reaction-time exercise designed to illustrate the danger posed by an attacker armed with a melee weapon at close range, that underscores how quickly a close-range threat can escalate. Tueller did his tests and studies at 21 feet (6.4 metres, 7 yards) because it was already common for officers to train to shoot from this distance. Tueller found that a person would be in danger if an attacker came at him from this distance. According to NRA publication Shooting Illustrated, the Tueller Drill evolved into a "21-foot rule," which is the idea that an attacker can close a distance of 21 feet within 1.5 seconds, and that therefore 1.5 seconds is generally taken to be the minimum response time facing a threat.

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