Like most people in California, you may be aware that there are several different types of tests that law enforcement officers can ask you to participate in before they choose to arrest you and charge you with a driving under the influence of alcohol offense. This battery of tests are often referred to as field sobriety tests because they are conducted in the field versus in a police station, jail or at another location.
According to FieldSobrietyTests.org, these tests are not used to measure your sobriety or lack thereof. In fact, they are not even able to do so. Instead, these field tests are used to provide results that either suggest you might be impaired. If the results indicate this, then an officer has legal grounds on which to make an arrest. One of these tests is called the horizontal gaze nystagmus and refers to jerking motion of the eyeball that is involuntary. This motion is called a nystagmus. In people who have consumed alcohol, the jerking may be more noticeable than in people who have not consumed alcohol.
Alcohol, however, is not the only factor that may excacerbate the jerking. Some medical conditions that involve neurological problems might make the motion more pronounced. The horizontal gaze nystagmus test is said to have an accuracy rate of 77 percent.
If you would like to learn more about the horizontal gaze nystagmus test used during a drunk driving investigation, please feel free to visit the field sobriety testing page of our California DUI and criminal defense website.