Attorney Carilyn Ibsen's Blog: Reliability of Nystagmus in a DWI/DUI Case

Horizontal gaze nystagmus is a common field sobriety test administered during a DWI/DUI investigation. The police officer holds a finger or pen a certain distance away from the person, making an assessment regarding their level of alcohol impairment. The officer testifies at trial to certain clues exhibited during the test that indicate impairment and then concludes whether the person is impaired for purposes of driving. The results of this test are used in conjunction with results from other field sobriety tests administered at the scene.

Shea Denning at the UNC School of Government highlighted the recent appellate court case State v. Goodwin. The Court concluded in Goodwin that a police officer must have sufficient experience, education and training in conducting and interpreting the results of the nystagmus test before the officer's testimony is admitted into evidence.

People will go back and forth regarding the accuracy of the nystagmus test. Some police officers will tell you it is one of the most accurate field sobriety tests they give in the field. Other police officers state that the accuracy can depend on the conditions surrounding the test and the subject.

I have spoken to a notable ophthalmologist and retinal eye surgeon in North Carolina about this test. He told me that this test was designed to be given under controlled settings. While the test can be highly reliable in controlled settings when administered correctly, he questioned the reliability of the test when given in the field by police officers. Also, the test may be completely unreliable based on a person's own medical issues.

The test is suppose to take over a minute to complete. I have rarely seen this. I have included a video below showing how the test is correctly administered. What happens in the field is much different.
https://www.youtube.com/watch?v=selZ9WrD7ac