Vermont DUI Horizontal Gaze Nystagmus (Eye) Test

If you are pulled over and suspected of drunk driving in Vermont, there are a handful of tests the officer can administer to evaluate your level of intoxication. There are typically two types of tests: field sobriety tests and chemical tests. Chemical tests use regulated medical devices to measure the exact amount of alcohol in a driver's blood, known as the Blood Alcohol Content (BAC). Field sobriety tests use simple physical tasks to evaluate a driver's level of coordination and alertness, both of which diminish with the consumption of alcohol.

Unlike chemical tests, results of field sobriety tests are determined using the sole judgement of the arresting officer. One of the most widely used field sobriety tests is the Horizontal Gaze Nystagmus Test (HGN test).

What Is Horizontal Gaze Nystagmus?

Nystagmus is defined as the involuntary jerking or stalling action that occurs in people's eyes when they are under the influence of alcohol or drugs. This condition makes it very hard for people to concentrate on one point in front of them for any prolonged amount of time. Officers will check for this condition by slowing waving a pen or small light back and forth in front of a driver's face and asking them to follow it with their eyes. If they fail to follow the instrument, the officer can use the results as probable cause for arrest or for the driver to take a chemical test.

Problems With The HGN Test

Although it is still widely used across the country, the HGN test is known to have a significant margin for error. Here are just a few reasons why a sober person might still fail the HGN test:

-Illness: There are a number of inner ear, sinus and head-related illnesses that could cause a person to fail the eye test. Migraines, ear infections, glaucoma, hypertension are just a few examples.

-Outside substances: Caffeine, prescription medication, nicotine and other, generally harmless, substances can cause erratic or problematic eye behavior.

-Stress, distractedness: The HGN test is most often a roadside test, which means there is the possibility that the test is administered on the shoulder of a busy road in other precarious places. This, as well as the overall stress of having to take the test, can mess with a driver's ability to concentrate, and therefore, affect the results of the test.