In our last blog entry, we discussed some ways to attack the validity of the Horizontal Gaze Nystagmus (HGN) test.
During a jury trial, the jury will review the video, but it is highly unlikely that they can pick up the subtle bounce or nystagmus of the eye from the video. They are essentially relying on the officer’s testimony that he witnessed clues of intoxication related to nystagmus. A jury will be extremely doubtful of the officer’s observations, if a Bexar County DWI attorney can demonstrate that the officer has written reports with mistakes, that his testimony differs from the video, and that he did not perform the HGN test according to NHSTA specifications.
An especially strong tactic is when the officer claims that the driver was swaying and unable to stand steadily. Well, the inevitable question when an officer testifies like this, is how on earth he could possibly estimate a 45 degree angle for onset of nystagmus if the driver is swaying? The officer will either claim he could detect the nystagmus before a 45 degree angle was reached on a person moving back and forth or that somehow the driver was able to stand still throughout the HGN field sobriety test. The officer will inevitably contradict himself and the jury will cast doubt on his credibility. Any swaying during the HGN will ultimately render the HGN test invalid. If the officer contends the driver was swaying but then remained still during the HGN test, the jury will question whether in fact the driver was intoxicated if he was able to stay still during the entire administration of the HGN test.