Utah DUI Cops’ Eye Test (HGN)…Is it Valid?

 The Horizontal Gaze Nystagmus Test is a field test that officers across the nation, including Utah, use to determine whether a person is impaired.  Is the test valid?  The officer is not an opthamalogist and uses no scientific equipment to check a person’s eyes.

He is not trained by anyone who has scientific training with the eyes.  On a good day, the National Highway Traffic Safety Administration studies say this test is at least 77% accurate at determining whether a person is above a .10 (now claim it is effective at .08).   A recent study that was published by the New Jersey Neuroscience Institute indicate that too many people have a natural nystagmus (involuntary bouncing/twitching of the eye).  Here are the highlights:

**GEN=Gaze Evoked Nystagmus

  • A significant number of normal subjects have physiologic GEN at gaze angles as small as 10°.
  • Studies suggest that it is present in over 50% of the normal population and is more common in fatigued subjects.
  • Despite the wide range of conditions other than alcohol toxicity which can cause GEN and even though the test and formulas are
    under extreme scrutiny, it is currently accepted by courts as evidence equal to chemical testing.
  • At 10° and 20° respectively, 21 % and 34% of the subjects demonstrated physiologic GEN.
  • We found an unexpectedly high frequency of GEN at 10° (21 %) and 20° (34%),which was similar at all ages.
  • The current minimum gaze angle of appearance of nystagmus at which the person "passes" is 45°. Not only does our study show that there is a significant amount of nystagmus occurring at
    smaller gaze angles, but our maximum angle on extreme lateral gaze averaged 42.7°; which was much less than the minimum amount required to "pass the test." The majority of our subjects (93%) would fail this test out in the field.

If an officer conducts a field test on anyone, regardless of alcohol consumption, there is a good chance he will see nystagmus.  Should the officer be allowed to testify that he saw bouncing eyeballs and therefore, the citizen accused was impaired?  Absolutely not!  The only person I want looking at my eyes is a trained eye doctor that is not looking to take me to jail.  There are too many variables when this test is given by an officer on the street.  The test is just too unreliable.  The link below is the study itself. 

www.utahduilawblog.com/uploads/file/PHYSIOLOGIC GEN OCCURS AT SMALL ANGLES BY WHYTE 2009.pdf


4 responses to “Utah DUI Cops’ Eye Test (HGN)…Is it Valid?”

  1. Yet another great post.

    It is a mystery to me how a test that is primarily designed simply for a quick and dirty screening test to rule in or rule out possible numerological issues has been hijacked and bastardized to supposedly represent and record alcohol intoxication to the exclusion of all other reasons.

    -Justin J. McShane, Esquire, Pennsylvania DUI Attorney


  2. In Commonwealth v. Sands 42 Mass. 184 (1997), the highest court in Massachusetts ruled that a police officers testimony in a DUI case regarding the Horizontal Gaze Nystagmus (HGN) sobriety field test was inadmissible without expert testimony. The Court ruled that Nystagmus could be a indicative of intoxication, but it is also the sign of numerous ailments. The Court reasoned that a lay juror could understand, from common experience and knowledge, that intoxication leads to diminished balance, coordination and mental acuity. However, the correlation between intoxication and an involuntarily jerking of the eyeball is beyond the common knowledge of a juror.

    Brian E. Simoneau,
    Massachusetts DUI Lawyer


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