Oklahoma's Oldest DUI Defense Firm

Attorneys Stephen G. Fabian Jr. and Brian P. Young

What Is The HGN Or Pen Test?

HGN stands for horizontal gaze nystagmus. Nystagmus is the involuntary jerking of the eyes when moving in a horizontal direction. Police officers, unfortunately, think this eye exercise is conclusive of a person’s level of intoxication. In fact, many officers only give this test and do not complete the other two tests in the three-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, 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 natural nystagmus. It is impossible to differentiate between nystagmus caused by alcohol and nystagmus caused by something else. The bottom line is that the HGN test is not scientifically reliable and is not an accurate test to determine impairment by intoxication.