What is the purpose of a roadside test? What does the flashlight test tell officers during a DUI stop? Is this an accurate and reliable test to tell law enforcement if you are intoxicated? What exactly is Nystagmus and how does it influence your roadside test?
The Horizontal Gaze Nystagmus test is used to assess the involuntary jerking of the eyes or Nystagmus. This test is used to judge the jerking of the eyes as the eye moves side to side. This jerking is not only involuntary but also unconscious; the subject is usually unaware that it is happening as well as having no way to control it. When someone is under the influence of alcohol, this jerking movement by the eyes is more noticeable and much more distinct. The more alcohol someone has consumed, the earlier the jerking will start as the eyes move to the side. The Nystagmus test is one of the most reliable roadside tests to date. When used in combination with the divided attention tests officers can very accurately judge who is under the influence of alcohol and who is not.
Prior to the Nystagmus test, the eyes are checked for the ability to follow and object together and equal pupil size. If the eyes do not track together or if the pupils are different sizes, this is pretty good indication that injury or medical disorders are causing the Nystagmus.
When the Nystagmus test is administered, each eye is checked separately. Each eye is examined for three specific
- As the eye moves from side to side, does it move smoothly or does it jerk noticeably? (Alcohol may cause a person’s eyes to exhibit a lack of smooth pursuit as they move from side to side.)
- When the eye moves as far to the side as possible and is kept at that position for several seconds, does is jerk distinctly? (Distinct Nystagmus at maximum deviation of the eye is another possible clue that an individual may be under the influence of alcohol.)
- As the eye moves toward the side, does it start to jerk before it has moved through a 45-degree angle? (Onset of Nystagmus prior to 45 degrees is another possible clue that an individual may be under the influence of alcohol.)
The higher a person’s blood BAC, the more likely it is that these clues will appear. The maximum number of clues that may appear in one eye is three; the maximum for any suspect is six, three for each eye. Research shows that if four or more clues are evident, it is likely that the suspect’s BAC is above .10. The reliability of this four or more clue criterion is 77 percent.
These are just a few ways that police can determine your level of intoxication during a roadside test. It is very important that you are aware of your mental and physical state while driving. Talk to an attorney if you have any questions about the above material. Contact an attorney if you are charged with a DUI or DWAI. Find out your options, potential punishments and any other information regarding a DUI. This is not legal advice. These tests are voluntary and are an extension of your Fifth Amendment rights; it is usually not in our client’s best interest to take these roadside tests. Contact your attorney to gain advice about your unique situation.
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By Shannon Lynch