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Standard Field Sobriety Tests in California and Defenses

Once the motorist is stopped, an arresting officer may request that the motorist to perform a series of “test” to determine if the motorist is intoxicated or not. California has three standard field sobriety tests: the Horizontal Gaze Nystagmus test, the one leg stand, and the walk and turn.

Under the Horizontal Gaze Nystagmus test, the officer first asks the motorist if she wears contacts or glasses. The officer positions the motorist to stand with her feet together and hands at her side, while keeping her head still. The officer is supposed to hold a stimulus (normally a pen, finger, or flashlight) approximately fifteen (15) or twelve (12) inches in front of the motorist’s face and move it left and right. Nystagmus is the involuntary jerking of the eyes that occurs for a myriad of reasons but normally occurs during alcohol intoxication.

Under the One Leg Stand, the officer requires the motorist to stand on one leg and extend the other leg six (6) inches above the ground. The motorist is to stare at the elevated leg and count out loud to thirty (30) seconds.

The walk and turn is the third test. The motorist is to stand heel to toe fashion with arms at the sides. The driver is instructed to take nine (9) heels to toes steps along a straight line, turn 180 degree and take another nine (9) heels to toes steps along a straight line. The motorist is to count the steps audibly and keep her arms at her side.

All three standard field sobriety tests are admissible. But they can be challenged for lack of foundation or other reasons.

A motorist can argue for lack of foundation. California retains the “Frye/Kelly” doctrine.  The Frye/Kelly doctrine states that new scientific techniques are only admissible when there is a preliminary showing of general acceptance of the new technique in the relevant scientific community. Although the Horizontal Gaze Nystagmus has been used for over thirty (30) years, it is still considered a new scientific technique. Despite previous claims, California courts are in agreement that the Horizontal Gaze Nystagmus test is a scientific technique and still applies under the “Frye/Kelly” doctrine. As such, testimony by police officers that they administered the Horizontal Gaze Nystagmus test is not enough to meet the “Frye/Kelly” doctrine. Rather, the prosecutor is required to produce expert testimony and scientific studies indicating that the Horizontal Gaze Nystagmus is widely accepted by the scientific community. Without such a showing, the officer testimony is insufficient for a driving under the influence conviction.

Moreover, the Horizontal Gaze Nystagmus test is a scientific test and requires a person with specific skills. Only certain officers are capable of performing this test. An officer testimony may be impeached for lack of knowledge or experience; such as not knowing what constitutes a Nystagmus and a common eye jerk. Furthermore, showing that the motorist has a congenital Nystagmus can challenge the officer’s testimony. A congenital Nystagmus occurs when a disease or condition causes the eye to jerk; such as after a stroke a person’s eye tend to jerk.

The one leg stand and walk and turn can be challenged by showing that the motorist generally lacks balance. After such showing, it becomes more complicated to prove if the motorist cannot walk and turn or stand on one leg because they were intoxicated or if they are generally unable to stand on one leg or walk and turn.


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