HGN Test Defense

It is also a test that police in North Georgia administer frequently during traffic stops when intoxicated driving is suspected. Though the NHTSA recognizes the HGN as a test that can indicate impairment, this test is not fool-proof. In fact, it has its disadvantages, which make admitting it as evidence problematic.

In Georgia, our DUI defense lawyer will investigate your case, including the types of and manner in which field sobriety tests like the HGN test were administered. At Johnson Law Firm, we use our skills and resources to ensure you receive the best representation possible. Contact us at (706) 230-5944 to schedule a consultation and learn more about how we will help you fight your DUI charge in North Georgia.

The Horizontal Gaze Nystagmus test is one of three standardized field sobriety tests used by the police in Georgia to help determine whether a driver is under the unlawful influence of alcohol or drugs.

The officer conducting the HGN test should provide clear verbal instructions to the driver. The police officer should tell the driver to stand still, place hands to the side, and keep head still. Then they must be properly instructed to look at a stimulus, like a pen or another object, and follow it with both eyes while the officer moves the stimulus from right to left.

The officer assesses the driver's eyes while moving the object from side to side. HGN tests, however, are very technical in their application. Proper administration involves specific requirements on distance between the stimulus and the driver's nose (12 - 15 inches), timing and length of holds (hold the stimulus for at least 4 seconds at the maximum deviation), and how many times and ways the stimulus is passed back and forth.

The HGN test is meant to measure the involuntary jerking of the eye – known as nystagmus. A driver with a high blood alcohol concentration may exhibit involuntary jerking of an eye as the driver gazes toward the side while following the stimulus.

Police look for three major clues while administering the HGN test. Each eye is assessed for these three clues, so there are actually a total of six possible indicators of intoxication. If the officer determines four clues exist, that is supposed to indicate the driver's blood alcohol content (BAC) level is above 0.08 percent.

Each clue requires specific motions or manners in which the stimulus is held or passed. Each clue also requires different timing, making proper administration critical for accurate results.

HGN tests can be challenged effectively by arguing against their reliability (these tests are highly subjective) or proving improper administration of the test (these tests require following strict and specific technical rules). Also, these tests can be challenged based on matters not associated with the test itself, but matters related to the driver or to the environment.

Keep in mind that there are more than 38 non-alcohol-related causes for nystagmus, and each of these can lead to a failed HGN test.