WINAMAC — As a federal law enforcement officer with the National Park Service, Pete Zahrt was administering what’s known as the horizontal gaze nystagmus test along a busy stretch of the Blue Ridge Parkway in Virginia, cars whizzing past at 60-plus mph, when it struck him: There has got to be a better way.
Part of the battery of assessments that comprise the standard field sobriety test, the HGN test measures nystagmus, or the jerking of the eyeballs, a relatively common response to visual stimuli that becomes more pronounced when a person is intoxicated.
To look for this, an officer will hold an object a specified distance from a suspect’s face and watch as the suspect, without moving, attempts to track the object back and forth along a horizontal plane according to a prescribed sequence of movements…