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    THE HORIZONTAL GAZE NYSTAGMUS TEST

    Were you wondering what the officer was doing when he was waiving his finger in front of your face?  This is called the Horizontal Gaze Nystagmus test, or as some cops call it, the HGN test.  What this test actually is, is the officer looking at your eyes to see if nystagmus occurs through a serious of subtests.

    WHAT IS NYSTAGMUS?

    Nystagmus in a nutshell is an abnormal jerky movement of the eye.  There is some questionable academic literature which finds that people with blood alcohol levels over the legal limit will have the presence of nystagmus in their eyes. 

    WHAT IS THE ACTUAL NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION TEST

    First, the officer checks for “equal tracking” by moving an object quickly across the subject’s entire field of vision to see whether the eyes follow the object simultaneously.

    Next, the officer is supposed to check for equal pupil size.

    Finally, the cop performs the actual test, which, in theory, is supposed to take place as follows:

    • LACK OF SMOOTH PURSUIT - The officer moves the object slowly but steadily from the center of        the subject's face towards the left ear. The left eye should smoothly follow the object, but if the eye exhibits nystagmus, the officer notes the clue. The officer then checks the right eye.
    • DISTINCT NYSTAGMUS AT MAXIMUM DEVIATION - Starting again from the center of the suspect's face, the officer moves the object toward the left ear, bringing the eye as far over as possible, and holds the object there for four seconds. The officer notes the clue if there is a distinct and sustained nystagmus at this point. The officer holds the object at maximum deviation for at least four seconds to ensure that quick movement of the object did not possibly cause the nystagmus. The officer then checks the right eye. This is also referred to as “end-point” nystagmus.
    • ANGLE OF ONSET OF NYSTAGMUS PRIOR TO FORTY-FIVE DEGREES - The officer moves the object at a speed that would take about four seconds for the object to reach the edge of the suspect's left shoulder. The officer notes this clue if the point or angle at which the eye begins to display nystagmus is before the object reaches forty-five degrees from the center of the suspect's face. The officer then moves the object towards the suspect's right shoulder. For safety reasons, law enforcement officers usually use no apparatus to estimate the forty-five degree angle. Generally, forty-five degrees from center is at the point where the object is in front of the tip of the subject's shoulder. 

    THE OFFICER’S QUALIFICATIONS TO GIVE THE TEST

    As you can see, the HGN Horizontal Gaze Nystagmus test is very complex test which requires a police officer to remember a bunch of different things when they do the test.  However, given that the HGN class that the officer took consists of an eight hour class in which they get a one and a half hour lunch break and learn how to testify about the test for a few hours, the cops usually don’t remember what they are supposed to do.  That is why when you watch the video of the sobriety tests, you will not be surprised to see the cops not doing the test right.

    SO WHAT HAPPENS WHEN THE POLICE OFFICER DOESN’T DO THE TEST CORRECTLY?

    Simply put, if the horizontal gaze nystagmus test is not performed correctly, then the court is required to suppress the test, as is required because of the Michigan Court of Appeals case of  People v Berger, 217 Mich App 213, 217; 551 NW2d 421 (1996).  This should be done at a pretrial motion, although I sometimes wait until trial to pull this off as the jury will see the true nature of the cop lying.