Overview of standardized field sobriety test variations

On Behalf of | Jul 20, 2023 | Field Sobriety Tests

Police officers use field sobriety tests to determine whether someone is too impaired to drive. While many different tests can be done, only three are considered reliable enough to be admissible in court.

The one-leg stand, horizontal gaze nystagmus and walk-and-turn make up the standardized field sobriety test recognized by the National Highway Traffic and Safety Administration. These standardized tests must be done precisely.

One-leg stand

During the one-leg, an individual has to stand on one foot and remain there for 30 seconds. The other foot must be approximately six inches off the ground. Impairment is suspected if the person sways, hops, puts their foot down or tries to balance with their arms.

Horizontal gaze nystagmus

The horizontal gaze nystagmus requires an individual to look at an object the officer moves while instructing the person to watch it. If the eye jerks in an exaggerated manner, impairment is likely. A sober person can likely smoothly follow the object as it moves.


The walk and turn involves walking heel-to-toe in a straight line for nine steps. A person then turns around to walk another nine steps. This task requires divided attention, which is something that an impaired person usually can’t handle.

After the field sobriety test

The field sobriety test is often done before a chemical test to determine the actual blood alcohol concentration (BAC) of the driver. When the standardized field sobriety test is done properly, it can accurately indicate impairment in 91% of cases. That increases to 94% when some explanations regarding false positives are accepted.

Several defense strategies are possible if a standardized field sobriety test is included in a criminal case. These include incorrect interpretation of the test, incorrect administration of the test and false positive results. It becomes more complicated to set a defense strategy if a BAC test indicates impairment, but even that evidence is not insurmountable. Seeking informed legal guidance should make it easier to determine the defense strategies that you’ll want to use to defend against DUI charges if you’ve recently been accused of driving while impaired.

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