Drunk Driving Defense, DUI Arrest - FAQs
6. What was the officer doing when he made me follow a penlight from the left to the right with my eyes?
The term for this FST is the horizontal gaze nystagmus
test. Nystagmus is a medical term to describe a particular eye oscillation. Supposedly, the steadiness of the eyes following the pen, and the degree at which the eyes begin to jerk indicate the level of alcohol in the blood of the suspect. When the police officer performs this test, he is attempting to judge if the angle is under 45 degrees to the side that the suspect’s eyes begin to jerk. If the angle is under 45 degrees, this typically means a blood-alcohol level over .05%.
Although the horizontal gaze nystagmus is a fairly new test, it is not permitted in many states. The medical community does not regard it as credible. Also, the majority of officers that perform this test are not medically trained in the area. Meaning, their ability to properly judge the angle, and identify nystagmus is not reliable. Unfortunately, aside from the many apparent flaws, this field sobriety test is accepted in the state of California.
