In a DUI investigation, there are three field sobriety tests that an investigating officer will typically administer. These are called the "standardized field sobriety tests." The tests included: the horizontal gaze nystagmus evaluation ("HGN" or eye test), the walk and turn evaluation (walking the imaginary straight line), and the one leg stand evaluation (where you balance on one foot for 30 seconds with your arms at your side.) These tests have been studied by the federal government and if administered properly, are supposed to be indicative of whether someone is under the influence of alcohol.
Of these three evaluations, the HGN test is supposed to be the most reliable. In this test, the officer is looking for “nystagmus” which is an involuntary jerking of the eye. Nystagmus is not something a person can hide or consciously not display. Central nervous system depressants, such as alcohol, cause nystagmus. Federal standards on field sobriety testing claim that there are actually three clues that the officer's use to check for horizontal gaze nystagmus. Officer's conduct the test on each eye for a total of six clues of impairment.
The Federal standards state that if the officer sees four or more of these clues, that can be an indicator that someone may be impaired by alcohol to the extent he or she should not be driving. There have been some studies done that say that four or more clues may mean that the driver has a blood alcohol level of .08 or more. The legal limit for DUI in Georgia is .08.
Of course, not everyone is a good candidate to participate in the HGN test. For example, recent head trauma from a car wreck can affect the results as can flashing lights. Moreover, even more of an issue is that police officer, even experienced DUI officers, are still human and may not conduct the evaluation correctly. Conditions in the field like rain, bad lighting, passing traffic and nervous and uncooperative drivers can affect how the officer administers the test.
We are DUI trial attorneys who have conducted DUI trials throughout the state. Frustratingly, many of the trial judges in the state of Georgia have allowed police officers to testify in court that people are, in fact, .08 as a result of taking an HGN test and displaying four or six clues therein.
Thankfully, due to the good work of some DUI attorneys in Georgia, officers are no longer free to make such ridiculous assertions. On October 2, 2017, the Supreme Court of Georgia released a new decision in the case of Spencer v. State.
In a nutshell, the Court found that an officer cannot equate four or more clues on the HGN with a BAC over a .08. simply by stating that he or she learned or heard that as part of their training and experience.
This is a big victory for many people fighting their DUI cases at trial who do not take a breathalyzer or blood test. The HGN test is a medical test that was never designed to be a determiner of alcohol or drug impairment.