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Basic Field Sobriety Test Information

Sobriety Test

When a person is under suspicion of driving under the influence of drugs or alcohol (DUI), the investigating officer will often conduct the Standardized Field Sobriety Test (SFST). The SFST is actually a battery of three separate tests, designed to determine whether a person is intoxicated or not. The tests were developed through research funded by the National Highway Traffic Safety Administration (NHSTA) and conducted by the Southern California Research Institute. The way a person performs on these tests is often used as “evidence” of a person’s intoxication. These tests are not foolproof, however, and any errors in the way that they were administered may be sufficient to have the case against you reduced or even completely dropped. California takes driving under the influence extremely seriously, and anyone facing a DUI case should be certain to consult with an experienced California DUI attorney as soon as possible.

Field Sobriety Tests

The three field sobriety tests administered in the SFST are the Horizontal Gaze Nystagmus (HGN), the Walk-and-Turn, and the One-Leg Stand. Each test is described in more detail below:

Horizontal Gaze Nystagmus (HGN): This test involves a law enforcement officer moving an object, such as a flashlight or pen, in a horizontal fashion and asking the person to track the object back and forth with their eyes. A sober person generally will be able to track the object smoothly. Furthermore, when a person is sober and they rotate their eyes to their periphery, an involuntary eye jerking occurs called Horizontal Gaze Nystagmus. However, if a person is intoxicated, the jerking will be more prominent and will occur at lesser angles. During the HGN test, the officer looks at the subject’s ability to track the object in a smooth fashion, the angle of nystagmus onset, and the severity of the nystagmus.

Walk-and-Turn (WAT): This test divides the subject’s attention between mental and physical tasks, a division of attention that should be relatively easy for a sober person, but substantially more difficult for a person who is under the influence. The officer directs the subject to walk in a straight line, heel to toe, for a certain number of steps, then turn on one foot and return in the same manner. Officers look for several different indicators of intoxication, such as the subject has difficulty following instructions, loses balance while listening to instructions, cannot take continuous steps heel-to-toe or walk in a straight line, swaying, waving arms or hopping to maintain balance, not counting the correct number of steps, or making an improper turn. Two or more mistakes can indicate intoxication.

One-Leg Stand (OLS): This is another divided attention test that judges a person’s ability to use their physical and mental capacities simultaneously. A subject must stand on one leg for thirty seconds while counting by the thousands. The officer looks for balance issues such as swaying, putting the foot down, waving arms, or hopping.

Contact a Sonoma County DUI attorney today for a consultation

The consequences of a DUI can be extremely serious, and can affect many aspects of a person’s life. As a result, it is important for anyone facing a DUI case to retain the representation of an experienced DUI lawyer immediately. Beck Law P.C. is committed to helping people facing DUI allegations bring their cases to the best resolution possible. Contact our office today to schedule a consultation regarding your Sonoma County, Lake County, or Mendocino County DUI case.

Photo Credit: OregonDOT via Compfight cc

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