Field Sobriety Tests

Help from a Cook County Criminal Defense Attorney

After being stopped by a law enforcement officer who suspects you of driving under the influence of drugs or alcohol (DUI), you will likely be asked to participate in field sobriety tests. These are tests that are usually used to evaluate your physical and cognitive state. There are three types of field sobriety tests that can be used-the walk-and-turn test, the one-leg-stand test and the horizontal gaze nystagmus (HGN) test. While these tests have long been used as evidence against those accused of drunk driving and drug-impaired driving, they can render inaccurate results. A capable attorney will be able to help you explore the weaknesses of these tests and craft a compelling defense.

If you live in Chicago, Illinois or any other part of Cook County, you can turn to Cook County Criminal Attorney Fred Mark Dry for step-by-step legal guidance. With more than three decades of experience in criminal law, Attorney Dry has the knowledge and resources you need for effectively handling your DUI case.

Three Things to Know About Field Sobriety Testing

There are three key points that you should be aware of if you are pulled over for suspected DUI and asked to participate in field sobriety testing. These points include the following:

  • If you are being asked to take field sobriety tests, the officer has detected the smell of alcohol or other signs of possible intoxication;
  • Your performance will be used by the officer to justify your arrest and prove your guilt;
  • You can refuse to take field sobriety tests without legal consequences, and the same applies for Portable Breath Tests (also known as the Preliminary Breath Test).

How Field Sobriety Tests Work

Below is an explanation of how each of the three field sobriety tests work. These descriptions also explain what law enforcement officers are looking for when they test you.

Walk-and-Turn Test:

A driver who takes the walk-and-turn test is required to walk in a straight line, heel-to-toe. The person taking the test must do this in one direction (taking a specific number of steps), turn on one foot and then walk heel-to-toe on the line in the other direction. According to information from the National Highway Traffic Safety Administration (NHTSA), officers administering this test are testing drivers for their ability to follow instructions while simultaneously performing physical tasks (a test of divided attention). Signs of impairment can include difficulty maintaining one’s balance and an inability to properly follow directions (such as taking the wrong number of steps).


This test is also a “divided attention” test. The test requires the DUI suspect to stand on one leg. The individual must have one foot raised about six inches above the ground while he or she counts slowly. The person is usually required to do this for about 30 seconds. If the individual has difficulty or is unable to keep his or her foot in the air or his or her balance, that person can fail the test.

Horizontal Gaze Nystagmus (HGN) Test:

The HGN test requires a person to follow a moving object with his or her gaze. The officer usually moves an object (such as a pen) horizontally in front of the DUI suspect and tells the individual to keep his or her eyes on the object. The officer looks for exaggerated jerking of the eyes, particularly when the person’s eyes move to the side. If the person’s eye jerks excessively or if the eye starts to jerk before reaching 45 degrees of the person’s center, this could be a sign of impairment. Another sign is if the individual is unable to smoothly follow the object with his or her eyes.

Challenging Your Test Results

The reason why field sobriety tests can be problematic is that there are many other factors besides impairment that can lead to a test failure. Balancing on one foot is something that can be difficult for many people, even when sober. Balance can also be compromised if the individual is made to take the tests on a rocky or cracked ground, or if the person has a physical disability or injury. Nervousness can easily make him/her get the directions confused or count the wrong number of steps in the walk-and-turn test. Furthermore, an officer’s failure to administer a test correctly can throw off the results.

These are just a few of the many possible defenses that can be used against field sobriety test results. To learn more about how to set up a strategic defense plan that can help you protect your rights and uphold your innocence, contact Attorney Fred Dry today!

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