Field Sobriety Testing

The Standardized Field Sobriety Tests (SFST) are a battery of three tests administered and evaluated in a standardized manner to obtain validated 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) and conducted by the Southern California Research Institute. A formal program of training was developed and is available through NHTSA to help law enforcement officers become more skillful at detecting DWI suspects, describing the behavior of these suspects, and presenting effective testimony in court. Formal administration and accreditation of the program is provided through the International Association of Chiefs of Police (IACP). The three tests of the SFST are:

Horizontal Gaze Nystagmus
, which 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. 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 or her eyes. The examiner looks for three indicators of impairment in each eye:

– If the eye cannot follow a moving object smoothly,

– If jerking is distinct when the eye is at maximum deviation,

– If the angle of onset of jerking is within 45 degrees of center.

, where 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:

– Swaying while balancing.

– Using arms to balance.

– Hopping to maintain balance.

– Putting the foot down.

, where 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:

If the suspect 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.

Should I refuse Field Sobriety Tests in Texas?

The Walk-and-Turn test and One-Leg-Stand test are “divided attention” tests that are easily performed by most unimpaired people. These tests require a suspect to listen to and follow instructions while performing simple physical movements. Impaired persons have difficulty with tasks requiring their attention to be divided between simple mental and physical exercises. But, many unimpaired people will have a problem hearing and concentrating enough to remember the instructions because of other factors such as location, traffic noise, weather and temperature, lack of sleep, and ADD.

You will be performing the field sobriety tests under the stress of a police investigation at 2 a.m. on the side of the highway or on Washington Avenue with a police car’s lights flashing in the background. You have not practiced the field sobriety tests, and if you do not complete the field sobriety tests perfectly then it is very likely you will be arrested.


NOTE: The links provided above are to videos of a police officer giving the proper instructions to a subject who then performs the field sobriety test flawlessly in a controlled environment.



– It is your right to refuse the Field Sobriety Tests

– It is your right to refuse the Breath Test and/or Blood Test

Also remember that if you Refuse, then you will be arrested and charged with DWI. So you have to ask yourself, what will happen if I do take the sobriety tests. The simplest thing to do is don’t drink and drive


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