What was that eye test the police asked me to perform?

What was that eye test the police asked me to perform?

That test is the horizontal gaze nystagmus or often referred to as the HGN test. Police officers are trained to detect the involuntary jerking of the eyes, which may, among other causes, be caused by consumption of alcohol. If an officer detects three clues in each eye, a lack of smooth pursuit, nystagmus at maximum deviation, and nystagmus prior to 45 degrees, he/she is trained to testify that it is likely the person was above a .08 body alcohol content [BAC], which is above the legal limit.