The Science Behind the Tueller Drill: Why Knives May Be More Dangerous Than You Think

If there’s one thing I know, it’s that right now someone is teaching a self defense class and talking about the 21 foot rule for knives. If there’s two things I know, it’s that they are probably teaching it wrong, as the Tueller drill is often misunderstood. This article is going to look at some great research on the Tueller drill to determine if edged weapons really are a deadly force threat within 21 feet.

For those of you who aren’t police officers, or self defense nerds, we need to cover what the Tueller Drill is. It was a drill that was created by a police trainer Lt. Dennis Tueller way back in 1983. I like to believe the first iterations of this drill required everyone to wear amazing jackets and fingerless gloves, but I have nothing to back that up.

The drill itself placed an assailant, armed with a knife, 21 feet away from a police officer. The bad guy then charged the officer and through enough trial an error it was discovered that an average officer could draw and fire two rounds when the bad guy started running at that distance.

This gradually became more and more popular through police training academies, and self defense schools. It is often referenced in use of force policies by many police departments, and nearly any officer knows what this drill is.

There is a problem though. No one has actually tested this drill scientifically. Sure, Dennis ran some participants through some scenarios, but this isn’t something that could be published in a scientific journal, as there wasn’t any scientific or statistical rigor applied. Now, however, we have some actual scientific research testing the validity of the Tueller Drill.

Here is a great video with the illustrious Mike Seeklander of the American Warrior Society covering more about the Tueller Drill.

A Scientific Examination of the Tueller Drill

This excellent research was conducted by Dr. William Sandel, Dr. M. Hunter, and Dr. J. Pete Blair. It was titled, “A Scientific Examination of the 21 Foot Rule.” Long time readers of this website will remember these guys from my previous articles examining CQB tactics, and one man room clearing techniques.

In their paper, they conducted three experiments. The first experiment determined the average speed someone could sprint 21 feet. To do this they used laser timing gates that precisely measured when the subjects started, and how long it took them to cover the distance.

They found that the average participant could cover 21 feet in 1.5 seconds, with the fastest running a 1.24 and the slowest a 1.83 second time. This average lines up exactly with the original tests. Score one for the 80’s!

Next the researchers asked how quickly an officer could draw and fire their weapon. These participants were police officers with 56% of them using a level two retention holster, like the Safariland SLS series. There were other holster types that were averaged into the overall time as well.

The officers were given a Glock Simunitions gun and were told to fire their weapon at a silhouette 21 feet away when a light went off. Their time was recorded by video and analyzed frame by frame to precisely measure how long it took to draw and shoot the man sized target.

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It took officers an average time of 1.80 seconds to draw and fire at the target once. Several officers had a lot of trouble clearing their holster adding time onto the average. The median time to draw and shoot one round was 1.73 sec, with the fastest time at 1.03 sec and the slowest time at 3.4 sec. Fourteen percent of the officers missed the target. This brings us to the last experiment the researchers conducted.

They had participants charge police officers with a shock knife. This knife emits a sound like a taser and will deliver a painful shock if touched to bare skin. The officers were instructed to fire one round if the subject charged at them.

Of the 57 officers who participated in this drill, 7 were not able to draw their firearm successfully. For those that actually got their shot off, the average time it took to draw and shoot was 1.43 seconds. The fastest officers shot in .93 sec and the slowest was 2.4 seconds. These officers hit their target 76% of the time. This means only 66% of officers were successful in hitting a target running at them from 21 feet.

While I find these results incredibly compelling for police officers, I think they are just as applicable to anyone who carries a firearm for defensive purposes. In my experience a concealed draw is about the same speed as a draw from a level two holster. Without any hard evidence, I would assume that your average concealed carry person would fail at a higher rate than these officers did, and they didn’t do a particularly good job in my opinion.

Discussion

It seems that from these experiments that the 21 foot rule is no good for an average police officer. The researchers did some math and they figured that 32 feet would give 95% of officers a chance to draw and successfully engage a knife wielding subject. Obviously, it is impractical to stay that far away all the time.

The researchers did conduct one more experiment where the officers were allowed to move, either by back peddling, sidestepping, or moving at a 45 degree angle away while the aggressor charged them. They found that sidestepping the attacker actually generate the most amount of additional time to engage the threat.

In that experiment the officer was touched by a knife 33% of the time they stood still, 25.6% of the time when quartering forward and away, 7.7% of the time when back peddling, and only 5.3% when they sidestepped. This is quite interesting as most trainers recommend moving at a 45 degree angle.

By now some of you are correctly pointing out that this is only one study, where one paint cartridge was fired, and this doesn’t represent a real lethal force engagement. You would be right.

Real World Examples

The biggest flaw with this drill come from movies. We assume that a good hit on the bad guy, will stop him. That is rarely the case. Consider the case of Buchanan v. City of San Jose.

Police received a call for a knife wielding subject. They initially made contact at a range of 130 feet. He started to jog towards the officers with a knife, intending to commit suicide by cop. They engaged him once he was 55 feet away from them. He then traveled a further 37 feet before he fell to the ground.

As any hunter can tell you. Shooting an animal rarely causes them to drop dead in their tracks, and humans are no different. Often times violent assailants are not physically incapacitated, they are psychologically incapacitated by the fear of being shot more. This case shows just how far a man can go who doesn’t fear dying.

Recommendations

I, and the researchers will point out that this research does not mean the 21 foot rule is now the 32 feet rule. This is simply one data point in a relatively sterile environment. It might be a 18 foot rule with ditch between you or a 3 inch rule with thick glass. The point is that the environment and the particular details of any situation will determine when a person becomes a lethal threat.

If you have further interest in learning to defend yourself, then I would seek out a reputable instructor. Preferably one who has a long history of teaching defensive tactics. Don’t just pick the guy with the best Instagram videos, and most followers. Now get out there, and start training!

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