If I’m pulled over, what types of DUI roadside tests can the officer ask me to perform?

If you are pulled over and a police officer suspects that you have been drinking, he or she will ask you to perform a series of field sobriety tests (FSTs). The driver will generally be asked to perform simple tests to measure their physical dexterity or mental acuity. These types of field sobriety tests are known as “divided attention” tests, because they test the types of abilities needed to operate a motor vehicle.

The officer uses these tests to try to establish probable cause to make an arrest for driving under the influence (DUI), driving while intoxicated (DWI) or operating a motor vehicle under the influence (OUI). It is important to know that in while in some states these tests are voluntary, other states will suspend or revoke or suspend your license for refusing to submit to these tests. FSTs are controversial because of their high failure rate for people who are not under the influence of drugs or alcohol.

Elements of Field Sobriety Tests

To help remedy the high failure rate of FSTs while sober, the National Highway Traffic and Safety Administration (NHTSA) created guidelines for the FSTs, to ensure that the tests given are more accurate. The NHTSA tests are called standardized filed sobriety tests. Many states now implement these tests when doing a preliminary test for sobriety.

There are three basic tests that make up the standardized field sobriety tests are the one-leg stand, the walk and turn, and the horizontal gaze nystagmus test. In the one-leg stand test, the officer will ask the subject to stand in front of him, and lift one leg off of the ground, usually for 30 seconds. The officer will watch to see if the subject’s balance seems particularly off. In the walk-and-turn test, the subject is asked to take a series of steps in a straight line, placing one foot directly in front of the other. After a few steps, the officer will tell the subject to turn, and walk back the same way.

To perform the horizontal gaze nystagmus test, the officer will ask the driver to look at an object (usually a pen) that they hold up, close to the drivers face. The officer will then tell the driver to watch the object as they move it. The officer is looking to see how “smooth” the eye movement is. If the eye movement is jerky, this is a sign that the driver may be intoxicated.

Law enforcement may ask you to do other types of non-standardized tests, which include, but are not limited to, counting fingers, standing with your feet together and tipping your head back, reciting the alphabet forward or backward, touching your nose with a finger while your eyes are closed, or counting backwards from a certain number.

Field Sobriety Test Flaws

Field sobriety tests are not perfect. Different individuals may not be able pass them even when they are sober. For example, jerky eye-movement, which will cause the individual to fail the horizontal gaze nystagmus test, can also be caused by sedatives, vision loss, multiple sclerosis, stroke or brain tumors. People who have certain medical conditions, injuries, are obese or are over 65 years of age often cannot do many of these physical tests, such as the one-leg stand or tipping the head back.

Case Studies: DUI Roadside Tests

Case Study 1: Failed Horizontal Gaze Nystagmus Test

John was pulled over by a police officer on suspicion of driving under the influence. The officer asked John to perform a horizontal gaze nystagmus (HGN) test, where he had to track the movement of a pen with his eyes.

Due to a pre-existing medical condition affecting his eye movements, John’s eyes appeared jerky, leading the officer to believe he was intoxicated. However, John was sober and his medical condition was the cause of the test failure.

Case Study 2: Inability to Perform One-Leg Stand

Samantha, a middle-aged woman, was stopped by a police officer who suspected her of driving while intoxicated. Samantha was asked to perform a one-leg stand test, but she struggled to maintain balance due to an old knee injury. Despite her sobriety, Samantha’s difficulty in completing the test led the officer to assume impairment.

Case Study 3: Challenging FST Results

Michael was subjected to a series of field sobriety tests after being pulled over for erratic driving. Although he believed he was sober, Michael failed the walk-and-turn and one-leg stand tests due to nervousness and unfamiliarity with the instructions. Dissatisfied with the FST results, Michael sought the assistance of a DUI attorney to challenge the validity of the tests in court.

Case Study 4: Non-Standardized Tests for Medical Conditions

During a DUI stop, Sarah, who had a medical condition affecting her vision, was asked to count fingers as part of the officer’s evaluation. However, her vision impairment prevented her from accurately counting the fingers, leading the officer to conclude that she was impaired. Sarah’s case highlighted the limitations of non-standardized tests in accounting for medical conditions.​

Getting Help

As stated, field sobriety tests are not perfect. Even NHTSA tests are not very reliable. The standardized tests only have a proven 65 to 77 percent reliability rating. This means that if you are asked to perform these tests and fail them, you should consult a DUI attorney about challenging the validity of your FST results.

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