What Is an Officer Looking for During the Horizontal Gaze Nystagmus Test?

  • May 25, 2017

    If you’ve been pulled over by the police and the police suspects that you may be intoxicated, he will use his training to embark on a series of field sobriety tests. This will help the officer decide whether or not to arrest you and pursue charges of DUI. One of the tests that the officer may give you is something called a horizontal gaze nystagmus tests. This is part of a grouping of tests that the National Highway Traffic Safety Administration has approved for standardization because this test will accurately detect impairment from drugs or alcohol.

    What is the Horizontal Gaze Nystagmus Test?

    This is considered to be one of the most accurate tests of all. This test is conducted when a police officer has the driver follow a pen with his eyes. The police officer is looking for certain responses from the eyes that can show that the driver is intoxicated.

    The involuntary rapid movement of your eye, either vertically or horixontally, is known as nystagmus. There are a few things that bring this on, including head trauma, disease, and alcohol. In layman’s terms, it is the involuntary jerking of your eyeball.

    To conduct this field sobriety test, the police officer is supposed to check your eyes to see if your pupils are the same size and to see if your eye is able to track an object as it is being moved from side to side at eye level. The police officer will then hold his finger or a pen about 12 inches from your face at eye level and move it back and forth, parallel to the ground in front of you. The police officer is looking for three things:

    The lack of smooth pursuit;
    The onset of nystagmus; and
    Distinct nystagmus at maximum deviation.

    Each of the above is counted as one point in the test, and the police officer grades each eye during the test, so there is a possibility of six points for grading your impairment. You fail the test if you accumulate four or more points.

    The Result of the Test

    It’s possible that the results of this test can be excluded from evidence when it’s proven that the test was not conducted according to the accepted standards. The argument is generally that the test is not reliable because the test was not properly performed. You could have a health condition, such as a lazy eye or astigmatism that could provide inaccurate results.

    Also, it would have to be shown that the officer properly pulled you over, to begin with, known as probable cause. A police officer cannot just pull you over because he “thinks” you’re driving while under the influence — he needs to have seen you commit another infraction, such as running a red light or speeding in order to pull you over. From there, if the police office suspects you are intoxicated, he can then start his investigation into determining whether or not to arrest you.

    If you’ve been arrested for DUI, it’s best to retain the professional services of a DUI attorney. Your attorney will look over all the evidence including field sobriety tests, to determine if all were conducted legally. Your attorney will also determine if there was probable cause to pull you over to begin with. While each case and situation are different, consulting with a DUI attorney is your best chances for a successful outcome.

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