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Do I have to perform Field Sobriety Tests?

This is a question I often receive after a client has been arrested for DUI. The answer, of course, is NO. Field Sobriety Tests (FSTs) are optional. They are a subjective tool used by law enforcement to strengthen the probable cause needed to make a DUI arrest.

The National Highway Traffic Safety Administration (NHTSA) developed three tests:

  • Horizontal Gaze Nystagmus (HGN),
  • Walk-and-Turn (WAT),
  • and One-Leg Stand (OLS)

Horizontal Gaze Nystagmus Test

HGN is an involuntary jerking of the eye that occurs naturally as the eyes gaze to the side. Under normal circumstances, nystagmus occurs when the eyes are rotated at high peripheral angles. When a person is impaired by alcohol, however, nystagmus is exaggerated and may occur at lesser angles.

Walk and Turn Test

In the Walk-and-Turn test, the subject is directed to take nine steps, heel-to-toe, along a straight line. After taking the steps, the suspect must turn on one foot and return in the same manner in the opposite direction. The examiner looks for eight indicators of impairment:

  • cannot keep balance while listening to the instructions
  • begins before the instructions are finished
  • stops while walking to regain balance
  • does not touch heel-to-toe
  • steps off the line
  • uses arms to balance
  • makes an improper turn
  • takes an incorrect number of steps

One-Leg Stand Test

In the One-Leg Stand test, the suspect is instructed to stand with one foot approximately six inches off the ground and count aloud by thousands until told to put the foot down. The officer times the subject for 30 seconds. The officer looks for four indicators of impairment, including:

  • swaying while balancing
  • using arms to balance
  • hopping to maintain balance
  • putting the foot down

Are Field Sobriety Tests a reliable way to test for DUI?

The argument is that if someone "fails" these tests, their BAC is over .08. However, the scientific validity of these tests is questionable and may have nominal significance in a DUI case.

When an officer stops someone who they suspect of DUI and communicates with them at the vehicle, they have, typically, made up their mind to arrest the suspect. The FSTs are therefore used to strengthen their case for a DUI arrest.

Arguably, if the officer already thinks the suspect is under the influence before they perform the FSTs, they will probably fail the tests. Furthermore, rarely are the FSTs performed under ideal circumstances. The terrain is usually unstable, it is late at night, cars are driving by, headlights are flashing, it may be dark, the officer is pointing a flashlight, and the person is scared or nervous. None of these conditions are ideal for performing well on any test – let alone a test to determine BAC.

If you've been arrested for DUI based off a field sobriety test, then you need to contact my office immediately for tough defense. I offer a free consultation!