If you have been pulled over at the side of the highway by a police officer and he or she thinks you may be intoxicated, then the horizontal gaze nystagmus test is one of the ways that the officer might use to make a decision whether to arrest you for DUI.

The horizontal gaze nystagmus (HGN) test is one of several so-called field sobriety tests that can be used to test for intoxication. The HGN test is, in fact, one of three standardized tests that are most commonly used to test for intoxication in Texas. Other tests used to test for DWI charges are the walk and turn test and the leg balance test.

Administration

The term “nystagmus” means a sort of twitching of the eye that can occur when someone has consumed certain substances, including alcohol. The test used is designed to see if one or other of your eyes twitches when asked to observe a moving object. Normally, when the test is carried out correctly during a DWI stop, an object like a pen is held up in front of one of your eyes and it is then moved sideways up to a certain point and then back again, while you are instructed to follow the movement with the eye without moving your head. Each eye is tested in turn.

What the police officer is doing is checking to see firstly if each of your eyes responds smoothly to the movement of the object and also if you develop a twitch (nystagmus) either during the movement of the object or at the furthest point sideways.

Test Flaws

The HGN test is held up as one of the most proven tests used by police officers when carrying out field sobriety tests during a DUI stop, but it has serious flaws. There are several reasons why someone stopped and asked to carry out the test may fail without being, in fact, intoxicated. The test must be carried out in accordance with strict guidelines by a fully trained officer and must be carried out in good light to have any potential validity.

This is often not the case. Also, there are many other reasons why a person may fail the HGN test without being intoxicated. This might be due to nervousness, fatigue or a medical disability amongst other reasons.

Refusing a Sobriety Test

If you are stopped by a police officer on suspicion of being DWI, there is no reason why you should agree to complete any field sobriety tests. These tests are not compulsory, even though many drivers do agree to do them because they feel intimidated. The main reason why these tests are given is to try and find a reason to make a DWI arrest.

If you are arrested for DWI, bear in mind that the potential penalties in Texas can be severe. Just because you have been arrested does not mean you are guilty. You can fight your DWI charge with the help of an experienced DWI attorney.