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Does the Horizontal Gaze Nystagmus test prove intoxication?

On Behalf of | Feb 16, 2022 | Drunk Driving

As you know, police officers use several tools to determine if an individual is incapacitated by alcohol or drugs. For example, a cop might ask you to stand on one leg for 30 seconds or walk heel to toe during the encounter.

Another sobriety test, called the Horizontal Gaze Nystagmus (HGN), involves examining the person’s eye movements during a DUI traffic stop. Although the HGN has a scientific background, many DUI defendants in Upper Marlboro, Maryland, do not know how the test works.

Why do you need to understand the HGN test?

The main reason is to help you determine whether the police administered the test correctly. Like other field sobriety tests, there is only one right way to perform the HGN. If a police officer conducted this test improperly, it could improve your DUI defense.

Is it solid proof of intoxication?

Horizontal Gaze Nystagmus refers to involuntary eye movements (jerking) when an individual gazes to one side or the other. Science has shown that impairment by alcohol and certain drugs can exaggerate these movements. The test cannot prove intoxication, but (when used in conjunction with other tests), it can help the police decide when to arrest a suspected drunk driver.

What conditions can skew the HGN test?

If there are bright or flashing lights in your vision, such as police car lights, it can affect the accuracy of the HGN. The police must also ensure that the object used to test your eyes is held only 12 to 15 inches away from your eye.

Although an improperly administered HGN might not make your DUI go away, it could help you and your advocate choose the best defense for your circumstances. Learning more about Maryland DUI laws can also help you overcome or reduce the severity of your situation.