What is the HGN (pen) test?
HGN stands for Horizontal Gaze Nystagmus. Nystagmus is the involuntary jerking of the eyes when moved in a Horizontal direction. The police Officers, unfortunately think this eye exercise is conclusive of a persons level of intoxication. In fact many officers only give this test, and do not complete the other two of the tests in the 3-test battery. Unfortunately, there is no scientific evidence that the HGN or any of the other so called Field Sobriety Tests, are scientifically reliable or accurate to determine if a person is too impaired to drive. There are approximately 35 other causes of Eye Nystagmus that have nothing to do with alcohol. Unfortunately the officers are not trained about these other causes, therefore, they never consider them as a possible cause and automatically blame the Nystagmus on Alcohol. In addition, there are many people who suffer from a Natural Nystagmus. It is impossible to differentiate between Nystagmus caused by Alcohol and Nystagmus caused by something
