Field Sobriety Tests in DUI Cases

The police will ask you to perform Field Sobriety Tests during a DUI investigation.

When a police officer suspects a driver of being under the influence of alcohol, the police officer will likely ask the driver to perform several coordination tests known as Field Sobriety Tests (FST). There are many different tests that officers administer, but there are only three tests that have been evaluated and approved by the Nation Highway Traffic Safety Administration (NHTSA): horizontal gaze nystagmus (HGN), walk-and-turn test, and one-leg-stand test. Officers frequently ask drivers to perform other Field Sobriety Tests (alphabet, finger-to-nose, etc.) that have no scientific reliability and are not governed by any standard.

Horizontal Gaze Nystagmus (HGN)

During this test, the police officer will use a pen or finger and move it from side to side in front of the driver’s face. The test is not whether the individual can track the pen, but whether the pupils jerk when the pen gets to the outer range. This “jerking”, or nystagmus, is an physiological reaction to alcohol in the system. The person will not feel the jerking and has no control over its presence. While it may indicate the presence of alcohol in your system, the officer may not use the test to suggest a level of BAC. When conducting the HGN test, the officer will look for the following:

• Eyes that cannot smoothly track the pen.
• The person demonstrates a sustained and distinct nystagmus at maximum deviation, or approximately 60 degrees from the center.
• Subject’s nystagmus beings before the eyes turn 45 degrees from the center.

Walk and Turn

During this test, the subject will be asked to walk nine steps in a straight line, turn, and walk back nine steps on the same line. The officer will look for the following indicators to suggest intoxication:

• Subject uses arms for balance.
• Subject cannot maintain balance during instructions.
• Subject does not take the proper number of steps.
• Subject steps off the line.
• Subject stops to regain balance.
• Subject fails to walk heel-to-toe.
• Subject beings to walk before the instructions are completed.

One-Leg Stand

During this test the subject is asked to stand on one leg while counting to themselves until told to stop. Indicators of intoxication are:

• Subject uses his arms to balance.
• Subject sways to regain his balance.
• Subject hops to regain his balance.
• Subject rests the raised foot down early.

The tests are administered to gauge a person’s coordination and are not a reliable indication of a person’s blood alcohol content (BAC) level.

Failure of one of these three tests usually results in the officer’s application of a preliminary breath test (PBT) to determine an individual’s sobriety. It is important to note that these tests are supposed to be used within strict guidelines and that many officers are not experts in conducting these tests. Further, a person is not required by law to submit to a preliminary breath test (PBT) at the scene of the driving.

Do I have to perform the Field Sobriety Tests?

You are not required to perform any tests at the scene of the traffic stop. A prosecutor may well argue that your refusal to participate is an indication of your knowledge of being intoxicated. There is no support for this argument under the law. An officer’s only reason for administering the Field Sobriety Test is to gather evidence against you for court.

You may lawfully refuse to take any Field Sobriety Test or preliminary breath test (PBT) at the scene. You are only required to provide a breath or blood sample if and when you are arrested for DUI.

For over 20 years, The Law Office of James J. McCoart, III, has vigorously represented those accused of Driving Under the Influence. If you, or your family member, are interested in a no-cost consultation regarding a DUI charge in Virginia, then contact The Law Office of James J. McCoart, III, by phone (703) 369-2734, or email.