Gwinnett County DUI: What Are Field Sobriety Tests?

Most DUI arrests in Gwinnett involve field sobriety tests. Drivers are usually asked to perform these tests outside of their cars while being evaluated by a police officer for DUI. As Gwinnett County DUI lawyers, among other things, we watch video evidence to determine how a client appears on the field sobriety tests.

Field sobriety tests are a series of physical and cognitive tests that law enforcement officers use to assess a driver's level of impairment due to alcohol or drugs during a traffic stop or DUI (Driving Under the Influence) investigation. These tests are designed to help officers determine whether there is probable cause to make an arrest for DUI.

Field sobriety tests are not the same as chemical tests (e.g., breathalyzer or blood tests) that directly measure a person's blood alcohol concentration (BAC). Instead, they are used to gather evidence of impairment based on a driver's behavior and performance as subjectively judged by a law enforcement official.

Common field sobriety tests include:

  1. Horizontal Gaze Nystagmus (HGN) Test: During this test, the officer asks the driver to follow a slowly moving object, such as a pen or flashlight, with their eyes while the officer looks for involuntary “jerking” of the eye (nystagmus). Nystagmus can be more pronounced when a person is impaired.

The HGN test was developed based on research conducted by the Southern California Research Institute (SCRI) in the early 1970s. Researchers sought to determine if nystagmus could be a reliable indicator of alcohol impairment. Their research and findings formed the basis for the HGN test as it is known today.

  1. Walk and Turn Test: In this test, the driver is instructed to take a series of steps, usually nine heel-to-toe steps along a straight line, turn around, and take nine heel-to-toe steps back. The officer observes the driver for signs of impairment, such as losing balance, stepping off the line, or not following instructions.
  1. One-Leg Stand Test: During this test, the driver is asked to raise one foot off the ground and count aloud for 30 seconds. The officer watches for signs of impairment, such as swaying, hopping, or putting the foot down before instructed.

The Walk and Turn Test and the One-Leg Stand test was developed as part of a battery of field sobriety tests in the 1970s and early 1980s. These tests were created to help law enforcement officers detect and assess impaired drivers on the road using simple-to-administer tasks with at least a patina of scientific respectability.

These field sobriety tests are considered standardized because they follow specific procedures and criteria recommended by the National Highway Traffic Safety Administration (NHTSA). Standardization is meant to provide consistency in the administration and evaluation of these tests across different law enforcement agencies.

But are they accurate?

It's important to note that field sobriety tests are subjective and rely on the officer's observations and judgment. Many factors, such as nervousness, medical conditions, fatigue, or physical disabilities, can affect a driver's performance on these tests.

Additionally, external factors like weather conditions and uneven terrain can impact the results. While field sobriety tests can be useful tools for law enforcement, they are not infallible and may not always accurately reflect a person's level of impairment.

As DUI attorneys we are skeptical as to the scientific applicability of the tests. There is a lot of room for error. Although they can indeed be compelling to a judge or jury if the client looks either great or terrible.

When you need proven local DUI lawyers, call us immediately.

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