Most people have watched movies or television shows in which scenes depict a character being questioned by officers for suspected drunk driving. The driver is generally asked to perform a series of tests, called field sobriety tests, before they provide a breath sample. This does happen in real life as well and it is important for people to understand what these tests are and what they evaluate.
As explained by the AAA DUI Justice Link, one of the field sobriety tests evaluates a particular function of the driver’s eyes. When a person’s gaze shifts to the periphery, the eye will naturally begin to jerk at some point. This is called a nystagmus. In a drunk driving investigation, one field test – the horizontal gaze nystagmus test – looks at this natural motion to determine if it is exacerbated. An overly pronounced nystagmus may be an indicator that the person is impaired by alcohol.
The HGN test does have the potential to incorrectly identify a person as intoxicated, posing unique issues for many people. Certain medications, such as those used to control seizure disorders, may result in a person having a more identifiable nystagmus. Other prescription medications known to be problematic for people required to take the horizontal gaze nystagmus test include those drugs classified as depressants.
If you would like to learn more about the horizontal gaze nystagmus test or other evidence collected by officers before you are placed under arrest for a DUI or OUI offense, please feel free to visit the field sobriety test page of criminal defense and drunk driving defense website.