The HGN Test in Kansas City

Horizontal Gaze Nystagmus

Nystagmus is defined by the World Book dictionary as "involuntary movement of the eyeballs, frequently a symptom of disease". HGN (Horizontal Gaze Nystagmus) is a test included in those recommended by the NHTSA (National Highway Transportation Safety Administration) as part of the Field Sobriety Test which officers use to investigate suspected DUI (Driving Under the Influence). This test is not generally admissible in the Kansas Court as evidence but may be allowed if the defendant is not represented by a savvy Kansas DUI attorney.

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The instructions to officers on administering this test are detailed but the scoring of the test depends greatly upon the officer's ability to follow the instructions exactly, accurately judge angles and correctly observe the eye's motion. The test starts with the officer holding a finger or other object in front of the right eye and having the individual follow the horizontal motion of the object to the right side with his or her eyes while keeping the head still.

The officer must take approximately 2 seconds to move the object from directly in front of the suspect's eye to the farthest point possible. This must be done again on the right eye, this time taking 4 seconds to reach the farthest point. Then the same two steps are done on the left eye. This test is based on a statement that the eye will begin jerking before reaching 45 degrees from center if the suspect is intoxicated and that an intoxicated individual cannot smoothly follow a slowly moving object with his eyes.

Once moderate or distinct jerking is observed the officer must stop moving the object to see if the jerking continues at that angle of the eye. Test instructions state that the jerking will start and be continuous at about 40 degrees if the suspect's BAC is 0.10. The officer will score 1 point for each eye for each of the following: jerking begins before 45 degrees; when the eye is turned as far to the side as possible jerking is moderate or distinct; the eye cannot smoothly follow the object's movement. A score of 4 points is a fail.

According to the instructions a correctly administered HGN test is accurate 77% of the time. This being the case, a determined DUI defense lawyer with the firm will fight to prevent any information concerning this test from being heard by the court. The legal team at our firm has a considerable reputation as committed and zealous advocates.

Call Martin & Wallentine to review your Field Sobriety Test and discuss your defense with a proven DUI lawyer.

Problems with HGN

In Kansas, the HGN currently isn't admissible in trial. However, it is a factor the judge may consider when determining probable cause. Interestingly enough, this actually worked against us recently at trial. Our client showed no clues for intoxication pursuant to the HGN tests results. However, we weren't allowed to use these test results at trial under the current status of the law. The current status of HGN can be found under the Shadden and Witte cases.

The National Highway Transportation and Safety Administration recommends moving the stimulus a specific speed, when checking smooth pursuit of the eyes during the HGN. Failure to follow that speed will cause many people, even those that are totally alcohol free, to appear to have nystagmus.

NHTSA recommends a speed taking two seconds to move the finger (or other stimulus) from midline to the far gaze. As DUI defense attorneys, we have watched many videos of the arresting officers administering the HGN test. It is often done poorly and too hastily.

1. The reliability of HGN and it's component parts, i.e., lack of smooth pursuit. Nystagmus at max deviation and an onset prior to 45° is problematic.
2. According to the largest study conducted to-date, 10% of the population have an onset of nystagmus before 45° with a zero percent BAC. And, another ten percent have an onset of nystagmus at 45° that are totally alcohol free.
3. Age has a direct affect on HGN when looking for smooth pursuit, which begins to decline in a person's early 30's.
4. HGN is a divided attention test. It is not a simple test as first thought. Studies have shown that the presence of smooth pursuit is heavily influenced by the presence of any undetected peripheral activity, i.e., cars going by, people moving around, etc. The test needs to be done in almost complete blackout conditions. That is rarely done. Most times, the suspect is out on the road, with cars flying by and often times with the officer's patrol lights flashing. Hardly fair or accurate.
5. Background activity can affect smooth pursuit and result in nystagmus, i.e., the officer's trying to perform the nystagmus test and in your periphery you see a semi barreling down the highway.
6. Numerous other things can cause nystagmus. Possible sources of nystagmus include Parkinson's Disease, Progressive Supra Nuclear Palsy, Cerebral Disorders, Encephalopathy, Alzheimer's Disease, Large Cerebral Lesions, Epileptic Seizures or any form of degenerative disorder. A number of psychiatric conditions can affect smooth pursuit including Schizophrenia, and Psychosis.
7. Nicotine affects smooth pursuit.
8. Nystagmus does not significantly affect vision acuity. Most people will move their head when looking at a target of more than 15° off center line. So trying to determine nystagmus onset or at max deviation at or around 45° is of little relevance.

Contact a Kansas DUI Attorney at the firm who is dedicated to defending a client accused of DUI.

We practice extensively and have represented hundreds of clients throughout Johnson County and cities including Olathe, Gardner, Lenexa, Overland Park, Shawnee, Leawood and Kansas City.