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3 Standardized Field Sobriety Tests Used in DUI Stops

The National Highway Traffic Safety Administration has developed standardized field sobriety tests to be used by law enforcement when determining driver impairment. These tests were developed, studied, and seen as the most reliable out of all field sobriety tests. However, that does not mean they are foolproof.

Many experts have proven these tests to be designed to make individuals fail, rather than provide accurate insight on their impairment. For example, a completely sober individual may fail a test due to physical disabilities or the complex and unique nature of the tasks involved. How many people normally practice walking heel to toe or balancing on one leg for extended periods of time?

Regardless, the more you understand about these tests, the better informed you will be when facing them in a serious situation. Remember, field sobriety tests are also not mandatory; but a chemical test is if you want to avoid an automatic driver's license suspension.

What are the standardized field sobriety tests?

The three tests are systematically administered. Depending on the responses of the person being tested, the officer may use this evidence to place the driver under arrest. It is suggested that the three tests, used in combination with one another, have a 91% accuracy of determining driver impairment.

The three tests are:

  1. Horizontal Gaze Nystagmus test: This is an involuntary jerking of the eye that occurs when the eye looks to the side. When someone has consumed alcohol, the jerking is more aggressive and starts earlier than someone that is sober. An officer will ask a driver to follow a pen or a flashlight with their eyes, looking for the inability of the eye to smoothly follow the object and the distinct jerking of the eye.
  2. Walk and Turn: This test requires that a suspect listen to and follow instructions while performing physical movements. The officer will ask the driver to take nine steps along a straight line, walking heel to toe. The suspect must turn on one foot and return in the same manner. Officers look for the inability to balance, not walking heel to toe, stepping off the line, using arms, improper turning, or failing to take the right amount of steps.
  3. One Leg Stand: The officer will ask the driver to stand with one foot off the ground and count out loud by the thousands. This will show if the suspect can balance without swaying, using their arms, hopping, or placing their foot down.

While these factors can indicate a level of impairment, the validity of the field sobriety test can be called into question. For example, Horizontal Gaze Nystagmus can be affected by the consumption of certain medications and physical impairments or geographical elements may limit how long a person can stand on one leg. Working with a DUI lawyer can help determine the best defenses to these tests.