If you are pulled over for a possible DUI, one of the first field sobriety tests that the officer will do is the horizontal gaze nystagmus test (or HGN test). The HGN test is commonly recognized as a “follow the pen” test. Many people think that the purpose of the HGN is to see if a driver can follow a moving object. However, that is not what the HGN is testing for at all.
As the eyeball tracks an object, it normally moves smoothly and without jerking. However, if you have enough alcohol in your system, your eyeball may appear to jerk or bounce as it follows a stimulus. The purpose of the HGN test is to see whether an individual’s eye has smooth pursuit or if it jerks while following an object. This would supposedly tell the officer how intoxicated the individual is.
Reliability of the HGN
The HGN is one of the most unreliable field sobriety tests. One reason is that the circumstances in which the HGN is administered must be fairly controlled in order to yield an accurate result. For example, if a police officer fails to turn off his flashing lights prior to the test and then faces you toward his car to perform the HGN, the officer would not get accurate test results. Also, the officer must put the object at a precise angle and distance from your face in order for the HGN test to be reliable. This is a common problem of the HGN test.
Challenging the HGN at Trial
If you are charged with a DUI, you should challenge the results of the HGN test. This is often the very first test that the officer performs. Therefore, challenging the HGN test and showing that it was done incorrectly can suppress all the other evidence the officer gathered during his investigation.
You will need an experienced DUI attorney to challenge the HGN test. Give us a call to learn more about our strategies for beating the HGN and other field sobriety tests.