How Medical Conditions Can Affect DUI Field Sobriety Tests

How Medical Conditions Can Affect DUI Field Sobriety Tests
If you are stopped under suspicion of driving under the influence (DUI), you may be asked to perform field sobriety tests, also known as FSTs. These are intended to determine whether or not you are impaired, but there is debate about their accuracy. In addition, some medical conditions and affect performance on DUI field sobriety tests, so it's important to keep this in mind. You do have a right to politely refuse these tests.

Types of Field Sobriety Tests

There are a variety of FSTs law enforcement officers may use. Only three are recognized by the National Highway Traffic Safety Administration (NHTSA) as standardized, and these are the most common. Here is what they are and how medical conditions may affect them:

Horizontal Gaze Nystagmus

When you track an object in your peripheral vision (greater than 45 degrees), your eyes will involuntarily twitch. This is known as nystagmus. Law enforcement officers use the horizontal gaze nystagmus (HGN) test to determine if this twitch occurs before the object is at an angle of 45 degrees or if there is a lack of smooth pursuit, which can be signs of impairment. Some medical conditions and other circumstances that can affect HGN results include:
  • Taking some medications, such as aspirin or anti-epilepsy drugs
  • Eye strain
  • Previous head injury, stroke, or other brain damage
  • Inner ear inflammation
  • Multiple sclerosis

Walk and Turn

The walk and turn (WAT) test involves walking nine heel-to-toe steps in a straight line while keeping your hands at your sides. After this, you will ned to turn and walk back to the starting position. A failure to stay balanced or a failure to follow directions can both be signs of impairment. Some medical conditions and other circumstances that can affect WAT results include:
    • Being more than 50 pounds overweight
    • Being more than 65 years of age
    • Previous head injury, stroke, or other brain damage
    • Inner ear inflammation
    • Back problems
    • Leg problems

    One Leg Stand

    The one leg stand (OLS) test, like the WAT test, relates to balance. The law enforcement officer will ask you to stay with one foot six inches off the ground with your toe pointed upward. You will need to keep your hands at your sides and look at the raised foot while counting. Since the signs of impairment for this test are similar to the WAT test, the medical conditions that can affect it are also similar. Anything that impacts your ability to balance can compromise the validity of the results.

    What to Do If You Are Stopped for DUI and Have a Medical Condition

    If you are stopped under suspicion of DUI and have a medical condition, keep in mind that field sobriety tests are voluntary. You can politely refuse and although you can explain your reasons to the officer, this is not required, and in many cases it is better to choose to remain silent until you can speak with an attorney. A DUI conviction has serious consequences, so it's important to choose an experienced lawyer.
    If you believe medical conditions could have affected the results of your DUI field sobriety tests, contact us today for a free consultation.
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