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Field Sobriety Tests

Regardless of whether you are intoxicated at the time you are pulled over, a field sobriety test can be unnerving. While these DUI tests often accurately reflect that a person is impaired by alcohol or drugs, several factors can lead you to fail the test even if you are not intoxicated. If you have failed a field sobriety test in Illinois, you need an experienced team of DUI defense attorneys on your side. Dolci & Weiland can help.

The Field Sobriety Test in Illinois: An Overview

A field sobriety test generally consists of three sub-tests: the one-leg stand, the walk-and-turn, and the horizontal gaze nystagmus test.

One-Leg Stand

This portion of the field sobriety test is designed to test your balance, which can be impaired if you are intoxicated. As its name indicates, during the one-leg stand, the officer will ask you to balance on one leg while holding the other leg about six inches off the ground. During the test, the officer will check for signs of intoxication such as:

  • Inability to balance, or swaying heavily while trying to balance;
  • Using your arms to balance;
  • Hopping while trying to maintain balance; and
  • Putting your foot down before you are told to do so.


Field sobriety tests also include a test called the walk-and-turn, in which an officer will ask you to walk heel-to-toe in a straight line, turn around, and walk heel-to-toe back to your starting point. There are several giveaways of intoxication that a walk-and-turn test can uncover. These include:

  • Inability to balance while listening to directions;
  • Taking the wrong number of steps;
  • Not walking heel-to-toe;
  • Using your arms to balance while walking;
  • Stopping while walking; and
  • Stepping off of the line when walking.

Horizontal Gaze Nystagmus (HGN)

The third of the three field sobriety tests is horizontal gaze nystagmus testing. Nystagmus--an involuntary jerking of the eyes--is a tell-tale sign of drunkenness for a police officer. A field sobriety test contains a horizontal gaze nystagmus (NGN) test to check for signs of driving while impaired. Clues which officers look for when determining whether a person is driving drunk include:

  • Inability to track a moving object smoothly with the eyes;
  • Continuous jerking of the eyes when looking as far to the side as possible; and
  • Jerking of the eyes when attempting to look down at a 45-degree angle.

To perform this test, an officer will move an object such as a pencil or his finger from side to side at nose-level in front of your face. If you are unable to follow the object with your eyes, or if your eyes quiver while looking sharply to the side, the officer may determine that you are intoxicated.

Problems with Field Sobriety Tests, and How to Challenge the Test

While field sobriety tests accurately show intoxication more often than not, there are several problems with each subpart of the test that can lead a person to fail the test despite being sober. If you have failed one or more portions of a field sobriety test, a criminal defense attorney may be able to challenge the results of the test by proving that the conditions in which the test was conducted were improper or showing that you have a medical condition which prohibited you from passing the test.

One-Leg Stand

When administering a one-leg stand test, an officer should ensure that the location of the test is level and dry. If the location where the test was administered was slippery or otherwise inappropriate for the test, you may be able to challenge the results of the one-leg stand portion of the test.

In addition to geographical problems that can cause inaccurate results, a medical condition may result in your failing the one-leg stand. Conditions which can impact this test include:

  • Inner ear conditions which can lead to balance issues;
  • Leg or foot problems; and
  • Being severely overweight.


As with the one-leg stand, an officer should ensure that the terrain for a walk-and-turn test is flat and dry. If the test is administered in an area with a slope, or on a surface which is wet or slippery, the test may produce an inaccurate result.

Several physical and medical conditions can also have a negative effect on your ability to pass the walk-and-turn portion of the field sobriety test. People often have issues with this subpart of the test if they:

  • Are elderly;
  • Have back or leg problems; or
  • Suffer from an inner ear condition which can affect balance.

If you believe that the conditions surrounding the walk-and-turn portion of your test were not conducive to your being able to pass the test, or if you suffer from a medical condition which prevented you from being able to complete the test, you may be able to challenge this portion of the field sobriety test.

Horizontal Gaze Nystagmus

While HSN tests are the most accurate of the field sobriety tests, intoxication is not the only cause of nystagmus. Jerking of the eyes can also be caused by medications and eye conditions. When performing an HSN test, an officer should check for signs that a medical condition could be causing nystagmus rather than intoxication. Signs of medical conditions leading to nystagmus include:

  • One eye performing drastically better than the other;
  • Difference in pupil size; and
  • Twitching in the eyes while holding a normal, unstrained gaze.

If you failed an HSN test due to a medical condition which causes you to be unable to track objects or results in eye twitching, your criminal defense attorney may be able to prove your innocence and show that the test showed an inaccurate result.

Facing a DUI in Illinois? We Can Help

If you have been charged with driving under the influence after failing a field sobriety test in Illinois, it's important to seek representation from a seasoned criminal defense attorney as soon as possible. The legal team at Dolci & Weiland are dedicated to providing top-notch representation for those who have been charged with alcohol-based offenses. Don't wait until it is too late to defend against your charge; to speak to a member of our team today, fill out an online contact form or call the office nearest you today; for our DuPage office, call (630) 261-9098, or for our downtown Chicago location, call (312) 238-9007.