If you’ve ever been stopped by law enforcement in California and suspected of driving under the influence, you might have encountered the dui eye test known as the Horizontal Gaze Nystagmus (HGN). This test is one of the primary roadside tools officers use to evaluate whether a driver may be impaired by alcohol or drugs. Understanding what the dui eye test entails, how it’s conducted, and the ways a DUI defense lawyer can challenge it is crucial for anyone facing DUI charges in California.
What Is the DUI Eye Test (Horizontal Gaze Nystagmus)?
The dui eye test commonly refers to the Horizontal Gaze Nystagmus test, which evaluates involuntary jerking of the eyes that occurs when a person looks to the side. This jerking, called nystagmus, can be natural but becomes more pronounced when someone’s blood alcohol content (BAC) is elevated.
During the dui eye test, officers look for three specific signs in each eye:
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Lack of Smooth Pursuit: The officer moves a stimulus, such as a pen or flashlight, horizontally in front of the suspect’s eyes. Normally, the eyes follow this movement smoothly. Jerking or twitching indicates possible impairment.
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Distinct Nystagmus at Maximum Deviation: The stimulus is held at the far side of the eye’s movement (called maximum deviation) for a few seconds. If the eye jerks distinctly here, it can be a sign of intoxication.
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Onset of Nystagmus Before 45 Degrees: When the stimulus moves toward the edge of the person’s vision, officers expect no jerking before reaching a 45-degree angle. Jerking occurring sooner can indicate impairment.
Each clue is counted per eye, making for a possible total of six signs. Generally, four or more clues suggest a BAC of 0.10% or higher, which is over California’s legal limit.
How Is the DUI Eye Test Administered?
When conducting the dui eye test, officers are trained to follow specific procedures to ensure accuracy:
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Proper Lighting: The test should be done in a well-lit area or using a flashlight to clearly observe the eyes.
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Avoiding Distractions: Police lights, environmental distractions, or bright light shining into the suspect’s eyes can interfere with the test.
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Clear Instructions: The officer will instruct the driver to remove glasses if worn and explain the test’s steps before beginning.
The officer then moves the stimulus horizontally, carefully watching for the three signs in each eye. The test typically takes just a few minutes and is part of the standardized field sobriety tests (SFSTs).
Factors That Can Affect the DUI Eye Test Results
While the dui eye test is considered a reliable tool, several factors can impact its accuracy:
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Medical Conditions: Neurological disorders, inner ear problems, or past injuries can cause involuntary eye jerking unrelated to intoxication.
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Medications: Some prescription drugs or over-the-counter medicines can mimic signs of impairment.
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Environmental Issues: Poor lighting, weather conditions, or flashing police lights may confuse or disrupt the test.
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Improper Administration: If the officer is not properly trained or fails to follow testing procedures, the results may be inaccurate.
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Natural Variations: Some people have natural nystagmus or eye jerking, unrelated to alcohol or drugs.
Because of these factors, the dui eye test should not be the sole evidence for a DUI charge but rather part of a larger investigation.
How a Defense Lawyer Can Challenge the DUI Eye Test
If you are facing DUI charges in California based in part on the dui eye test, a knowledgeable DUI defense lawyer can analyze and challenge the test results in several ways:
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Questioning Test Administration: A lawyer can investigate whether the officer followed proper protocols, such as proper lighting and instructions.
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Highlighting Medical Issues: Any medical history that might explain involuntary eye jerking can be introduced as a defense.
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Examining Environmental Factors: Lawyers can argue that poor conditions or distractions interfered with accurate observation.
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Scrutinizing Officer Training: The defense can question whether the officer was properly trained and certified to administer the HGN test.
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Expert Testimony: Experts in vision, neurology, or toxicology may be brought in to dispute the validity of the dui eye test findings.
By raising these challenges, a DUI defense lawyer can weaken the prosecution’s case and protect your rights.
Why the DUI Eye Test Matters in California DUI Cases
In California, DUI charges can carry serious consequences including fines, license suspension, and even jail time. The dui eye test plays an important role because it provides law enforcement with a quick assessment of impairment. However, it is only one piece of evidence among others like breathalyzer results and witness observations.
Because of the test’s subjective nature and potential inaccuracies, it’s essential to have a legal advocate who understands the nuances of the dui eye test and can ensure that your case is fairly evaluated.
What Should You Do If You Are Asked to Perform the DUI Eye Test?
You are not legally required to perform field sobriety tests, including the dui eye test, in California. However, refusing may lead to immediate arrest or license suspension. Before deciding, it’s best to be aware of your rights and the potential consequences.
If you do perform the test, stay calm, follow instructions carefully, and be mindful that improper performance may be used against you.
Final Thoughts
The dui eye test (Horizontal Gaze Nystagmus) is a commonly used method by California law enforcement to detect impairment. While it can provide useful information, it is not infallible and must be properly administered and interpreted.
If you are facing DUI charges that involve the dui eye test, consulting with an experienced DUI defense lawyer is critical. They can scrutinize the test procedures, challenge questionable results, and work to protect your rights and freedom.
Contact Southwest Legal for Expert DUI Defense
If you or a loved one has been charged with a DUI in Southern California, don’t leave your future to chance. The DUI defense attorneys at Southwest Legal specialize in DUI defense and understand the complexities of the dui eye test and other field sobriety procedures. Contact us today for a free consultation and get the knowledgeable representation you deserve.
