The Standardized Field Sobriety Test (SFST) is a series of three tests administered and evaluated in a standardized manner to obtain valid indicators of impairment and establish probable cause for arrest. These tests were developed as a result of research sponsored by the National Highway Traffic Safety Administration (NHTSA).   Our law firm owns a NHTSA training manual – the same one used to train police officers!

There are 3 tests the police typically use. Even if the police officer administers these 3 tests properly and all signs of impairment are exhibited by the suspect, there is only a 65-68% chance that the person suspected is above the legal limit!

The 3 roadside tests or “exercises” are:

  • Horizontal gaze nystagmus

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

An alcohol-impaired person will also often have difficulty smoothly tracking a moving object. In the HGN test, the officer observes the eyes of a suspect as the suspect follows a slowly moving object such as a pen or small flashlight, horizontally with his eyes.

  • Walk and Turn

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 seven indicators of impairment: 1) if the suspect cannot keep balance while listening to the instructions, 2) begins before the instructions are finished, 3) stops while walking to regain balance, 4) does not touch heel-to-toe, 5) uses arms to balance, 6) loses balance while turning, or 7) takes an incorrect number of steps.

NHTSA research indicates that 68% of individuals who exhibit two or more indicators in the performance of the test will have a BAC of 0.10 or greater.

  • One-leg Stand

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 (One thousand-one, one thousand-two, etc.) until told to put the foot down. The officer times the subject for 30 seconds. The officer looks for four indicators of impairment, including 1) swaying while balancing, 2) using arms to balance, 3) hopping to maintain balance and 4) putting their foot down.

NHTSA research indicates that 65 % of individuals who exhibit two or more such indicators in the performance of the test will have a BAC of 0.10 or greater.   In reality, if a police officer has asked a suspect to perform roadside exercises, that suspect is going to jail.

Police officers have many incentives to make DUI arrests. Instead of giving the suspect a chance to demonstrate that they are not impaired, the police officer is taking notes during these exercises (and most likely ordering the tow truck to take your car following the arrest) for courtroom presentation.  This can be seen on most DUI videotapes and demonstrates the officer’s mindset that you are going to be arrested regardless of how you do on the exercises.

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