Traffic Stops and Horizontal Gaze Nystagmus (HGN)

So you were stopped for speeding. You have your driver’s license, vehicle registration, and proof of insurance but the police officer says you have “watery” eyes and that he can smell the “odor of intoxicants.” At this point can you be arrested from drunk driving? The answer at this point is probably no.

The officer is going to ask you to step out of the vehicle so that he can do further investigation. This usually involves having you perform Standard Field Sobriety Tests (“SFSTs”). I would note that the National Highway Traffic and Safety Administration (“NHTSA”) has only accepted three specific SFSTs as generally accepted indicators of alcohol impairment: Horizontal Gaze Nystagmus (“HGN”), Walk and Turn (“WAT”), and One Legged Stand (“OLS”).

The NHTSA Instructor Guide, a 648 page manual, is used to train new police officers. Police officers are taught to administer these three tests uniformly to each person who is suspected of operating a motor vehicle under the influence of alcohol. HGN is a test where the police officer instructs the driver to follow (with his or her eyes) a stimulus to the left and to the right. The officer notes the angle at which the pupil starts to exhibit “nystagmus” (an involuntary jerking of the eye). Early onset of nystagmus prior to or at a 45 degree angle is a clue associated with a high blood alcohol concentration.

According to the NHTSA, studies show HGN to be 77 percent reliable in determining whether a driver has a blood alcohol concentration over .08. The NHTSA lays out very detailed procedures for officers to follow when administering the HGN test, as well as clues to look for when scoring the test.

One of the procedures officers are to follow is to use a flashlight or finger and to position it 12-15 inches from the suspect’s eyes. Then move the stimulus. The movement of the stimulus consists of a total of at least 14 passes. These passes are divided into four stages or segments and each eye must have two passes for each segment, except for the initial equal tracking pass, which requires one for each eye. The first segment is designed to confirm equal tracking and equal pupil size. The officer is required to rapidly move the object from the center, to the person’s far left, to the person’s far right, then back to the center position. This segment should take at least two seconds.

The second segment is a set of four passes. In this segment the stimulus is moved from the center position to the person’s far left and back to the center position twice for each eye. The stimulus should be moved at a speed that takes at least two seconds from the center position to the side position. At a rate of four seconds per eye, per pass (two seconds out and two seconds back to center), this phase of HGN should take at least 16 seconds. In this segment the officer is look for smooth pursuit.

The third segment of four passes is designed to determine whether the person has distinct nystagmus at maximum deviation. This is the point at which the eye has moved fully to one side and cannot move any further. The stimulus is moved from the center position to the far left at a rate of at least two seconds, held for at least four seconds, and then moved to the center position at the same two second rate. In this segment each pass for each eye should take at least eight seconds and the four passes together must take at least 32 seconds. The officer must observe “distinct” nystagmus to score a clue for that eye.

The fourth and final segment is designed to determine whether the onset of nystagmus occurs prior to the eye’s movement to a 45 degree deviation. In this segment the stimulus is moved very slowly, at a rate that would take at least four seconds to move the stimulus to the person’s shoulder, or at a rate of no more than 10 degrees per second. Once the officer thinks he sees nystagmus, he is required to stop moving the stimulus and hold it steady to confirm the presence of nystagmus. Assuming an onset angle of 30 degrees and the stimulus being held for two seconds to confirm continuation of nystagmus, each of the four passes of the eye must take eight second (three seconds out, two second hold, three seconds back). The four passes together must take at least 32 seconds.

It is extremely rare for police officers to correctly administer the HGN test. Judges too often allow this to go on. The tests are to be administered in a very detailed sequence. Failure to do this correctly should result in a Judge rejecting the results of the HGN test, thereby reducing the chances of conviction. Too often defense attorneys do not look at HGN and simply take the police officer’s report that he did the test correctly, when in fact they did not administer the test correctly.

A good DWI defense attorney takes the time to get the police video and observe how the officer administered the HGN test. More times than not, it was administered incorrectly.

Alfred P. Brandt has spent 35 years reviewing these videos and has challenged the officers’ compliance with the HGN test and has successfully argued for dismissal of drunk driving charges based on the officer not properly administering the HGN test. Contact Alfred P. Brandt for a free review of your drunk driving case. If you have a criminal case in Calhoun County, Lenawee County, Hillsdale County, Washtenaw County, Jackson County, or Ingham County, contact Mr. Brandt about your case.

The information on this website is for informational purposes only. Nothing in this blog should be taken as legal advice for an individual case. This information is not intended to form an attorney-client relationship.

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