The first standardized field sobriety test Mississippi DUI officers are trained to administer is the Horizontal Gaze Nystagmus test (HGN). This test requires the driver to follow a pen or other object with his eyes.
What is Nystagmus?
Nystagmus is the involuntary jerking of the eyes. A person generally does not know his eyes are jerking, as it is virtually undetectable by the person who displays these symptoms. Studies have shown that alcohol and certain other drugs cause nystagmus. Officers are trained to use the HGN test to discover whether a driver has nystagmus in his eyes.
How is the HGN test performed?
Mississippi DUI officers are trained to conduct the HGN test using several separate and distinct steps, in a specified order.
The officer must first instruct the driver to stand with his heels together and his hands at his side. If the driver is wearing glasses, the glasses should be removed. Once this is done, the officer must instruct the driver to follow his pen or finger (or other object) with only his eyes, and to continue following the object until told to stop.
After instructing the driver, the officer must hold the object 12-15 inches from the driver’s nose, and slightly above eye level. When the officer places the pen in the proper position, the officer must “medically clear” the driver to perform the test. This is done by checking to see that the driver’s pupils are the same size. If the pupils are not the same size, this may indicate a head injury, and the test should not be performed. At the same time, the officer should also watch the eyes to see if the eyes jerk even while staring straight ahead. This is called Resting Nystagmus. Resting nystagmus is indicative of a medical condition. In this situation, the results of the test are likely to be invalid.
The next step is for the officer to check to see if both eyes track the pen equally as it moves. This is done by moving the pen side-to-side at a certain speed, for a certain period of time. Officers are trained to check both eyes for equal tracking. If one eye lags behind the other as the pen is moved, there is a high probability that the nystagmus is caused by a medical condition, as opposed to alcohol.
Assuming the officer finds that the driver has equal tracking in both eyes, he will then check for the following “clues” of alcohol impairment:
a. Lack of smooth pursuit: this is defined as the eyeballs jerking as they follow the pen from side-to-side.
b. Distinct and sustained nystagmus at maximum deviation: this occurs when the eyes are jerking when the pen is moved as far to the side as the eyes can follow, and held there for a certain period of time.
c. Onset of nystagmus prior to 45 degrees: this clue occurs when the officer observes nystagmus while moving the pen to the side slowly, before reaching a 45-degree angle to the driver.
Evaluation and scoring by the DUI Officer
The HGN test is scored as follows: If the officer finds a lack of smooth pursuit, that equals 2 clues (1 clue per eye). Where the officer additionally finds distinct and sustained nystagmus at maximum deviation, this results in two more clues, for a total of four clues. Finally, if the officer observes onset of nystagmus prior to 45 degrees, then an additional 2 clues are added, for a total of six (6) clues.
What do the clues mean?
According to the National Highway Traffic Safety Administration (NHTSA), where a driver has four or more clues, it is likely that his blood alcohol concentration (BAC) is above .10% (when the original studies were done, most States, including Mississippi, had a per se DUI percentage of .10). NHTSA also states that the HGN test is 77% accurate in predicting a BAC of more than .10.
What is Mississippi DUI law on the HGN?
The Mississippi Supreme Court first addressed the HGN test in the case of Young v. City of Brookhaven, 693 So.2d 1355 (Miss. 1997).
Under Mississippi law, scientific testing has to pass rigid standards before it may be admitted into evidence. In Young, the Court held that the HGN was a scientific test. The Court also held that “the HGN test is not generally accepted within the scientific community.” Scientific testing that is not generally accepted within the scientific community is not allowed into evidence because it is considered unreliable. For this reason, the Court held that in Mississippi DUI cases, the results of the HGN test are not admissible as evidence that the driver was impaired, or to prove that the driver was under the influence.
The Court did, however, allow the results of the HGN to be used as probable cause to arrest a suspected drunk driver and offer the driver a chemical test to determine his BAC. Even so, the Court stated that this evidence could be presented only to the Judge in determining probable cause. Under no circumstances may the State introduce this evidence in the presence of the jury.
The fact that the Supreme Court stated that HGN is not generally accepted in the scientific community is reason enough for a driver to refuse to take this test.
What are the problems with the HGN test?
There are several troublesome issues with the HGN test, which make its use in criminal cases problematic. These issues include:
a. Officer Error: While this post may seem long, I have set forth the “short” version of HGN testing. This test has exacting requirements for the administration and scoring of the test. In order for the results to be valid, the test must be given in precisely the manner specified by NHTSA. Any deviation from the testing protocol will likely make the results of the test unreliable. In my experience, almost no Mississippi DUI officers administer the test correctly or with any consistency. I also regularly encounter officers who not only administer the HGN test incorrectly, but also do not even know how to correctly give the test. Because the likelihood of Officer error is high, the HGN test cannot be relied upon in determining whether a person is under the influence of alcohol.
a. Other Causes: There are several different causes of nystagmus, and even many different types of nystagmus. Horizontal gaze nystagmus may be caused by unknown medical problems, physical abnormalities, and even head trauma. In these cases, while the officer may find nystagmus, it is not necessarily caused by alcohol impairment. In the case of medical problems or physical abnormalities, the driver may not even know these problems exist. For example, DUI officers are trained that nystagmus may be caused by brain tumors. A brain tumor is something that the driver may not even know he has. In this situation, an officer will testify that he saw nystagmus which was indicative of alcohol impairment, while the truth of the matter is that the nystagmus was not caused by alcohol. The problem is that the driver, not knowing he has a tumor (or other disease), will have no way of bringing forth evidence to rebut the officer’s claim. In addition to being inherently unfair, the possibility of such a result casts doubt on the reliability of the HGN test.
Don’t take the HGN
As you can see, the deck is stacked against a driver who takes the HGN test. Additionally, it is likely that the DUI officer will not administer the test correctly. The law does not require you to take the HGN or other field sobriety tests. If you are offered the horizontal gaze nystagmus test, you should respectfully tell the officer that you do not wish to take the test.
The Gulfport DUI lawyers at Crowley & Ray have passed a certification course in administering the HGN test, and we’re the only DUI lawyers on the Gulf Coast who have this certification. If you have been arrested for DUI in Gulfport, Pascagoula or elsewhere on the Mississippi Gulf Coast, please contact us for a free initial consultation.
