Horizontal and Vertical Gaze Nystagmus Test (The ‘EYE TEST’)

There are several types of field sobriety tests (FSTs) used by law enforcement officers while investigating DUI in Utah. Being arrested for DUI can be a very unnerving experience. If you are charged with DUI in Utah, be sure to hire an experienced Utah DUI lawyer who will fight to protect your rights. The attorneys at Greg Smith and Associates are seasoned Utah criminal defense lawyers who will work to obtain the best possible resolution of your case.

One of the most commonly used FSTs is the Horizontal and Vertical Gaze Nystagmus (HGN) test. Nystagmus is involuntary jerking of the eyes. Utah Prosecution Council, Driving Under the Influence Prosecution Manual (2007), https://www. sentencing.utah.gov/ProsecutionManual/chapter8.pdf.

This movement occurs whenever the eyes move from side to side. When a person is intoxicated, the jerking motion is magnified. Pennsylvannia v. Muniz, 496 U.S. 582, 585 FN 1 (1990). The same is true for Vertical Gaze Nystagmus (VGN). With VGN the officer looks for the jerking motion of the eyes as the suspect gazes up and down.

How is the test performed? An officer performs the test by asking a suspect to hold his or her head still. Then the officer directs the person to follow the tip of the officer’s pen (or other object) with the person’s eyes. The officer looks for three clues in each eye.

First, lack of smooth pursuit. This means that the eyes shake as they move from side to side. This shaking movement of the eye is much more noticeable when a person is impaired.

Second, distinct nystagmus at maximum deviation. When the person’s eyes are as far as possible to one side, the officer looks for distinct and sustained jerking movements of the eye. An officer should observe a person’s eye at maximum deviation for a minimum of four seconds. Nat’l Highway Traffic Safety Admin., Horizontal Gaze Nystagmus: The Science & The Law, https://www.nhtsa.gov/people/injury/enforce/ nystagmus/ hgntxt.html (last visited Oct. 17, 2011).

Third, the officer looks for onset of nystagmus prior to 45-degrees. This means that before the eyes reach a 45-degree angle while gazing towards the side, the officer looks to see if the eyes have begun jerking.

The officer performing the HGN test should look for each clue individually in both eyes. An officer may observe a total of six clues-three in each eye. Utah Prosecution Council (2007).

The higher a person’s blood alcohol concentration (BAC), the greater the likelihood the officer will observe these clues. According to research, the appearance of four or more clues indicate that the person’s BAC is greater than 0.10. The test is 77% accurate when four or more of the clues appear. This test is effective because nystagmus is involuntary and unnoticeable by the DUI suspect. Therefore, a person cannot deceive the test. Id.

The attorneys at the Affordable Legal Advocates are experienced DUI defense lawyers. They have handled numerous DUI cases in Utah and understand the correct protocol that every police officer should follow for administering field sobriety tests. Give us a call.

Recent Post
Call Now