Horizontal Gaze Nystagmus, or more commonly known as “The eye test” is one of the three standardized field sobriety tests created by the National Highway Traffic and Safety Administration (NHTSA). 

The test was created to identify drivers who have been operating their vehicles while under the influence. 

Horizontal Gaze Nystagmus is the lateral jerking movement of the eye balls that is akin to the movement your eyes make when you sharply look far to the side using your peripheral vision.

The term “Nystagmus” is the technical term for rapid involuntary movement of the eyes. 

This occurs when there is some form of irregularity in the inner ear system of the driver. 

One stimuli that causes this movement is alcohol as it hinders your ability to fully control the mobility of your eye muscles.

“The eye test” is conducted by a police officer and is administered by the officer moving his penlight in front of the driver’s eyes about one foot away. 

The officer will ask the driver to follow the light with his or her eyes. 

While the driver is doing this, the officer examines the pupils of the driver to see the angle at which the eyes are twitching. 

If the police officer notices that your eyes are twitching at a certain angle, this is seen as a sign of having a high blood alcohol level.

Accuracy of the DWI Eye Test

The eye test is a fairly new examination, but it is also one of the most accurate. 

Unlike the one leg stand test and the walk-and-turn test, the eye test actually examines an involuntary bodily spasm that is brought about by drinking alcohol. 

It is not designed to have you fail like the other two tests. 

Aside from having a serious issue with your eyes, there is no reason why you should have Horizontal Gaze Nystagmus at all. 

The stimuli that is measured by the eye test makes it the most accurate of the three field sobriety tests, yielding an approximate 77 percent accuracy rating in detecting blood alcohol contents that exceed the legal limit.

An issue that remains prevalent with the eye test, despite its perceived accuracy rating, is the administration of the test itself by police officers. 

Officers are still called to use their own discretion in deciding whether a driver manifests the tell-tale signs of drunkenness, leaving human error as an ever constant factor, and increasing the need of skilled Houston DWI lawyers to protect those wrongfully accused.

If you or a loved one has been subjected to a field sobriety test and have taken the eye test, or you have any general questions about field sobriety tests, contact Trichter & LeGrand today for a free consultation with one of our expert criminal defense attorneys in Houston.


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