Get Answers From An Experienced Attorney Phone Number 717-435-8830

On Your Side In Challenging Times

What is a field sobriety test?

Being stopped for suspicion of drunk driving is intimidating. Before making an arrest; however, the police officer may try to have motorists submit to a battery of tests that evaluate the driver’s balance, coordination and ability to divide their attention to multiple tasks.

Field sobriety tests

The field sobriety test is admissible in court, measures the driver’s ability to complete these tasks and may form the basis for DUI charges. The test results, however, depend on the police officer’s subjective evaluation.

Usually, a police officer will ask the driver to submit to a breath or chemical test to confirm their blood-alcohol content if they fail any field sobriety test.

Three tests

The standard field sobriety test involves a battery of three tests. The first test is the horizontal gaze nystagmus.

The horizontal gaze nystagmus measures the involuntary jerking of the eyeball, which happens to individuals when they rotate at high peripheral angles. But when a person is intoxicated, the eye jerking becomes more pronounced and occurs at lesser angles.

When conducting this test, the officer will ask the motorist to follow a pen, flashlight or other moving object slowly from side to side. The officer tries to determine whether the jerking is different when the eye is at maximum deviation, the jerking angle onset is within 45 degrees or if the eye cannot smoothly follow that object. Drivers are likely to have a BAC of at least .10 if four or more clues appear between the eyes.

The walk-and-turn test involves the driver walking nine steps, heel to heel along a straight line, turning on one foot and returning nine steps in the opposite direction. A driver is usually considered legally impaired if they do one of the following:

The one-leg stand test involves the officer asking the driver to stand with one foot approximately 6 inches off the ground. The driver must count, beginning from one-thousand-one, until the officer tells the driver to put their foot down. Over 30 seconds, the officer watches the motorist to determine whether they do any of the following:

Being sober

** People may fail a field sobriety test even if they are sober. Certain health conditions, disability, age, injury, and medications can cause failure. Drivers should tell the police officer if these circumstances exist.


** Motorists may refuse a field sobriety test without being penalized. But police may arrest them and require chemical testing if there is probable cause. Failure to submit to chemical testing is grounds for license suspension.

Attorneys can help motorists with their DUI defense. They can help them seek the best resolution of charges under the circumstances.