Do sober individuals fail field sobriety tests? Simply put, yes. In fact, field sobriety tests, or “FSTs,” are notoriously known to be untrustworthy. Yet, law enforcement agencies continue to use field sobriety tests to gauge a person’s coordination, balance, and simple motor skills when they are suspected of driving under the influence. The National Highway Traffic Safety Administration designated three FSTs as the standard for law enforcement; the Horizontal gaze Nystagmus (HGN) Test, the Walk-and-Turn Test, and the One-Leg Stand Test. Other FSTs include the Rhomberg Balance Test, the Finger-to-Nose Test, and the Finger Tap Test.
More than you would think, officers subjectively determine that someone has “failed” the FSTs only for it to be determined later that the suspect was, in fact, sober. How?
Stress/Nervousness: It goes without saying that people are both stressed and nervous when they are pulled over and asked to step out of their vehicle. Not to mention that the person is performing the FSTs in front of an audience of on-looking drivers. Officers regularly “fail” a person when they demonstrate trouble following simple instructions. However, stress and nervousness can cause a lack of concentration which may cause someone to make simple mistakes when trying to follow instructions.
Inner Ear Problems: Lack of balance is key indicator of intoxication and, as such, it is one of the symptoms that officers look for when conducting the FSTs. Unfortunately, there are many things that can cause a lack of balance, many of which have to do with the inner ear. The inner ear contains a small organ called the labyrinth that helps us maintain balance. When the labyrinth is disrupted, balance is negatively affected. Things that can disrupt the labyrinth include infections and illnesses, head trauma, age, and tumors, to name a few.
Physical Problems: A person may have trouble standing on one leg for 30 seconds if they have bad knees or a bad back. Similarly, it may be very difficult for a person to walk heel-to-toe in a straight line if they are in pain from bad knees or a bad back.
Age and Weight: People who are older or who are overweight will also likely have trouble performing many of the tests that require coordination and balance.
Tiredness: While it may be extremely dangerous to drive while tired or sleep deprived, it is not the same thing as driving while intoxicated. Lack of sleep can cause many of the same symptoms as intoxication; poor balance, lack of coordination, trouble performing fine motor skills. Furthermore, someone who is sleep deprived will also display a law enforcement favorite indicator of intoxication; bloodshot, watery eyes.
Officer Bias: The officer is going to see what he or she wants to see. The suspect would not be performing the FSTs if the officer didn’t already think that the person was drunk. Therefore, even before performing the tests and subjectively determining that the person has failed, the officer believes the person to be drunk. Let’s be honest, if an officer does witnesses someone pass the FSTs, I doubt they’d say, “Well, I guess I was wrong.”