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Failing an HGN test can put you at risk of DUI charges

On Behalf of | Jul 16, 2022 | DUI/DWAI |

If a Colorado police officer pulls you over and asks you to step out of your vehicle, you can logically assume that he or she suspects you of impaired driving. However, a police officer must be able to show probable cause to arrest you for drunk driving. To determine whether such cause exists, a patrol officer might ask you to take a Horizontal Gaze Nystagmus (HGN) test.  

Learning about this test ahead of time can help you make informed decisions if you wind up in a situation where you’re asked to take an HGN or other field sobriety test during a traffic stop. There are several things to keep in mind regarding an HGN test, one of which is to note that it’s an eye test.  

Basic facts about HGN tests 

An HGN test is an eye test but not, specifically, a “vision” test. If you agree to take an HGN test, the police officer administering the test is going to be closely observing your eye movements. The officer in question might use an object, such as a pen, or his or her own finger, to administer the test. The officer will ask you to track the movement of the object in a vertical or horizontal direction, using only your eyes, without moving your head or any other part of your body.  

The term “nystagmus” refers to an involuntary jerking movement of the eyeball. This erratic movement is often present in a person who has consumed alcohol, when he or she tries to track an object using only eye movement. A police officer will closely observe your eyes as you track the object that he or she is holding, or you may need to hold a static gaze at your maximum field of peripheral vision. If the officer believes that your eyeballs are showing nystagmus movements, you might fail the test. 

What happens if you fail an HGN test? 

In Colorado and most other states, failing an HGN test constitutes probable cause to make a DUI arrest. In short, this means that you might be tracking an object during a traffic stop one minute and riding in the back of a police car the next, if the person who administered the test marks your score as a failure.  

HGN tests and all field sobriety tests are voluntary  

One of the most important things to remember regarding an HGN or other field sobriety test is that you’re under no obligation to comply with a request to take them. Even if you’re sober, you might still receive a failing score on an HGN or another field sobriety test. The way the police officer personally interprets his or her observations as you perform an HGN or other test has a significant impact on your score.  

It’s possible that one police officer might issue a failing grade when another would have passed you for the same test. This is why many people refuse to comply with requests to take field sobriety tests. You might determine that it’s best to take the test then deal with the outcome if you wind up in police custody for suspected DUI. If that’s the case, remember that you’re guaranteed an opportunity to obtain legal support and to refute the charges in court, if you choose to do so.