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May 24, 2017 | admin Los Angeles DUI and Horizontal Gaze Nystagmus (“HGN”)
When law enforcement officers investigate a drunk driving offense, there are a lot of different things that they look for. They learn these cues when they become police officers. Of course, the officer checks for bloodshot eyes and the smell of intoxicants. They’ll ask you if you’ve been drinking and how much.
As an experienced Los Angeles DUI attorney can tell you, if law enforcement suspects you of drunk driving, they can also put you through a series of physical tests. These tests are called field sobriety tests. They are intended to give the officer indicators as to whether you’re over the legal limit to operate a motor vehicle.
One of these tests is called the horizontal gaze nystagmus or HGN test. The test might seem like pseudo science but it’s actually one of the three field sobriety tests that has been scientifically tested and verified nationwide by the National Highway Traffic Safety Administration. The other tests that have been tested and verified nationwide are the walk and turn and the one leg stand test. If a driver indicates for alcohol use on all three of these tests, there is seventy-seven percent chance that the person has a blood alcohol level of a .10 or higher per 210 liters of breath.
Many people think that field sobriety tests are pass or fail, but this is not the case. Rather, a driver shows indicators while performing the test that they are over the legal limit. In the case of the walk and turn and one leg stand test, these indicators can be anything from not following directions to waving arms to wavering during the movements. The officer can make a determination as to whether a driver’s performance on the field sobriety tests indicates that they’re over the legal limit.
A nystagmus is a jerking eye movement that occurs when a person’s eyes are at certain angles. Horizontal nystagmus is when a person’s eyeballs jerk when they’re looking side to side. Vertical nystagmus occurs when a person looks up and down. Unless a person has an inner ear problem or a problem controlling their eyes, nystagmus often occurs only when a person is under the influence of alcohol or drugs.
These substances depress the central nervous system and cause eye jerking. The more alcohol or drugs in a person’s system, the more jerking. In some cases, a person can be under the influence of drugs without any nystagmus, so this test isn’t perfect, especially when an officer investigates drug use. Some seizure medications can cause false positives with this test, too.
To perform an HGN test, the officer uses a pen or their finger. They hold the object or finger a foot away from the person’s face. They instruct the person to follow the pen or finger with only their eyes. They move it to the left or the right and then look in the corner of the person’s eyes to see if there is a nystagmus.
If the eyes move smoothly, it’s a sign of sobriety. When the eyes jerk in the corner, it’s a sign of intoxication. Additionally, if the eyes start to jerk even before the corner, it’s a sign of severe intoxication.
The HGN test is only as good as the person giving it. If you’re charged with drunk driving in Los Angeles, it’s important to have an experienced DUI attorney evaluate your rights. They can review the police report and demand any available videos to investigate whether the officer properly performed the HGN test. Your DUI attorney can use their training and expertise to advocate for you.