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Why Drivers Fail Sobriety Tests

Officer giving a field sobriety test

Law enforcement officers use field sobriety tests to determine whether a person is under the influence of alcohol. Three of the tests have been validated by the National Highway Traffic Safety Administration (NHTSA), while others have not. Many do not realize that these tests are not as accurate as most people think, and you can fail them even if you are perfectly sober.

Walk and Turn Test

In this test, the officer may ask you to walk in a straight line, heel to toe for nine steps before turning around and taking the nine steps back. They can then ask you to turn in a specific manner, keep your arms at your sides, look at your feet, and count out loud. Officers are told to issue these commands in rapid succession in order to test your mental acuity.

Even though this sounds somewhat simple, the truth is that many people could be susceptible to possible unease or shakiness that leads an officer to conclude they are intoxicated. Furthermore, it can be challenging to comprehend unfamiliar instructions the first time around.

One Leg Stand Test

The second test requires you to raise your foot approximately 6 inches off the ground while keeping the bottom of your other foot parallel to the ground. With foot raised in the air, the driver is asked to count aloud from 1 to 30. It has been tested and found to be 65% accurate in determining whether someone is under the influence of alcohol. This is an incredibly challenging test, even for sober drivers, because the testee must maintain a good balance to ensure the test's passing.

Unfortunately, even swaying during this test could be seen as a failure.

Horizontal Gaze Nystagmus Test

In this test, the officer moves a pen, pencil, or finger in front of you. In theory, your eye is supposed to jump in response if you have been drinking. This is one of the most inaccurate and unscientific of all the tests, as this specific response to that stimulus occurs naturally in people for at least 38 different reasons. In other words, a person with glaucoma, influenza, or vertigo will fail this test while sober. Multiple NHTSA studies have found HGN tests' accuracy to only be accurate about two-thirds of the time.

The Problem with Field Sobriety Tests

Even when the three tests validated by the NHTSA are used, their combined accuracy is only 83% at most. This means that the test results are invalid for at least 17% of people determined by the tests to be under the influence of alcohol.

Field sobriety tests are also very subjective. In some cases, individuals have been determined to be intoxicated when they have had only one drink. Certain people are also more likely to fail the tests, including drivers who are over 65 years old, more than 50 pounds overweight, or have medical problems.

Lastly, there is a possibility that the test is administered improperly by an inexperienced officer, skewing the results.

Virginia's Premier DUI Defense Firm

If the police arrest you for drunk driving after allegedly failing a field sobriety test, find an experienced DUI defense attorney who can help you fight your criminal charges. An attorney will examine the tests you performed and all other evidence in your case to possibly get your criminal charges reduced or dismissed.

Contact Tillotson & Martin, LLC at (757) 568-7978 for help defending your rights and protecting your future.