Horizontal Gaze Nystagmus Can be Challenged

Posted Tuesday, July 18, 2017 by Andrew Charles Huff

The Horizontal Gaze Nystagmus or HGN Test is a nationally-recognized test used by police on those suspected of Driving Under the Influence (DUI). Officers examine a person’s eyes for any evidence of “Nystagmus,” or a slight jerking of the eyeballs. Although there are a number of other causes of Nystagmus, alcohol is one of them.

The majority of states including Washington recognize that the Horizontal Gaze Nystagmus (HGN) test is scientific evidence, which generally require expert testimony along with testimony the test was administered correctly by the officer. The case of State v. Baity is the primary decision in our state which limits the application and ultimate use of this test in any trial.

But whether the issue is admissibility or weight, the crucial issue in most DUI trials is whether the test was administered in accordance with the National Highway Traffic Safety Administration (NHTSA) guidelines for HGN. One study observed that the HGN test was administered in the field incorrectly over 90 percent of the time. Therefore, it’s critical to know and understand the NHTSA guidelines and requirements for a successful challenge to this test. I have never tried a case involving the HGN without knowing and having an actual copy of the NHTSA Instructor and Student Manuals from the Standardized Field Sobriety Testing Course. In both trial and even Motion Hearings challenging the evidence, I have literally brought out the manuals and flipped to the relevant pages when questioning the arresting officer. Strict compliance with the NHTSA protocol and requirements is required. Without strict compliance, the validity is compromised and the results are functionally meaningless.