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3 Field Sobriety Tests and Their Role in a DUI Case

A State Trooper pulls over a truck to perform field sobriety tests on the driver

When stopped for a driving under the influence cause, law enforcement can operate several field sobriety tests to determine impairment of the driver by alcohol or drugs. Explained are the tests operations and their role in a DUI charge.

Field sobriety tests are standardized tests that law enforcement officers use to assess whether a driver is impaired by alcohol or drugs. These tests are typically conducted roadside during a traffic stop and are used to establish probable cause for an arrest. The results of field sobriety tests can be used as evidence in a DUI (driving under the influence) case, but they are not foolproof and are often challenged in court.

Field Sobriety Tests:

There are three main field sobriety tests that are recognized by the National Highway Traffic Safety Administration (NHTSA): the one-leg stand, the walk-and-turn, and the horizontal gaze nystagmus (HGN) test.

The One-Leg Stand Test

The test requires the driver to stand with one foot about six inches off the ground and count out loud until told to stop. The officer will look for several clues that may indicate impairment, such as swaying, hopping, or using the raised foot to balance.

The Walk-and-Turn Test

The test requires the driver to take nine steps in a straight line, heel to toe, turn around on one foot, and then walk back in the same manner. The officer will look for clues such as losing balance, taking the wrong number of steps, or not following instructions∙

The Horizontal Gaze Nystagmus Test (HGN)

This test involves the officer asking the driver to follow an object, such as a pen or finger, with their eyes as it is moved from side to side. The officer is looking for nystagmus, which is an involuntary jerking of the eye that can be a sign of impairment.

In addition to these three tests, there are several other field sobriety tests that are not standardized but are sometimes used by law enforcement. These include the finger-to-nose test, the Romberg alphabet test, and the finger count test.

It is important to note that field sobriety tests are subjective and are dependent on the officer’s interpretation of the results. Factors such as the driver’s age, weight, and physical condition can all affect their performance on these tests. In addition, environmental factors such as weather, lighting, and the surface of the road can also impact the results.

Roles in DUI Case

The results of field sobriety tests are often used as evidence in a DUI case, but they are not the only evidence that can be used. Other types of evidence that may be used in a DUI case include the results of a breathalyzer test, the driver’s behavior and appearance, and any damages to the vehicle.

One of the main challenges to the use of field sobriety tests as evidence in a DUI case is that they are not always reliable. Studies have shown that these tests are only accurate about 75% of the time. This means that there is a significant margin of error, and an individual who is not impaired could fail a field sobriety test.

In addition, there are several ways that a skilled defense attorney can challenge the results of field sobriety tests in court. For example, they may argue that the tests were not administered correctly or that the officer did not have probable cause to administer the tests in the first place.

Despite these challenges, field sobriety tests are still widely used by law enforcement as a tool to identify impaired drivers. While they are not guaranteed, they can provide valuable evidence in a DUI case and are often used in conjunction with other forms of evidence to establish probable cause for an arrest.


It is important for individuals who are facing a DUI charge to understand their rights and options when it comes to field sobriety tests. If you are stopped by an officer who wants you to perform a field sobriety test, you do have the right to decline. However, it is important to note that in some states, declining a field sobriety test can result in an automatic suspension of your driver’s license.

If you do decide to take a field sobriety test, it is important to follow the officer’s instructions and to remain calm. It is also a good idea to try to remember as much as possible about the circumstances of the test, as this information may be useful to your attorney if you decide to challenge the results in court.

If you have been charged with a DUI, it is important to seek the advice of a qualified attorney as soon as possible. An experienced attorney can help you understand your rights and options and can provide you with the legal representation you need to protect your interests.


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