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The three standardized field sobriety tests

On Behalf of | May 10, 2024 | Criminal Defense

Imagine this hypothetical scenario. You are driving down a Texas highway in an erratic manner and you see blue lights in the rearview mirror. You pull your vehicle to the side of the road, and the officer who pulled you over suspects you are under the influence of alcohol. In this situation, he or she would likely ask you to step out of the vehicle to perform field sobriety tests to gauge your sobriety. 


These field sobriety tests assess an individual’s basic motor skills that are impaired by alcohol consumption — skills such as balance, coordination and the ability to multitask. While administering these tests, the officer will also assess your ability to follow instructions. The Standard Field Sobriety Test (SFST) established by the National Highway Traffic Safety Administration consists of three separate tests scientifically proven to show intoxication: the walk-and-turn, the one-leg stand and the horizontal gaze nystagmus (HGN). 


The walk-and-turn test is to assess balance. For the walk-and-turn test, the officer will ask you to take at least nine steps, heel-to-toe, in a straight line. Then, turn on one foot and return nine steps heel-to-toe in the opposite direction. During the test, the officer looks for several indicators of impairment, such as loss of balance, taking the wrong number of steps or the inability to follow instructions. 

Horizontal Gaze Nystagmus (HGN) 

Horizontal gaze nystagmus is a jerking of your eyeball when your eyes rotate at high peripheral angles. This happens to everyone, but after consuming alcohol, the jerking movements become more exaggerated. When administering the HGN test, the officer asks you to follow a moving object, usually a flashlight or pen, slowly from side to side. The officer looks to see if your eyes can’t follow the object smoothly and if your eyeball jerks at maximum deviation. 

One Leg Stand 

With the one leg stand test, the officer will assess your balance. The test is as the name implies: the officer asks you to stand on one leg while lifting your other leg about six inches off the ground as you count out loud for about 30 seconds. The officer will look for swaying or using your arms or hopping to keep balance. 

What if you are under arrest? 

Sobriety tests are optional, and you can refuse to take them. Keep in mind, though, that if you refuse to take these tests, you can still face arrest if the officer suspects intoxication, and then they may conduct further testing. Even if you pass field sobriety tests, you can still face arrest if an officer thinks you may be under the influence of alcohol. Fortunately, those in Texas who are arrested and charged with a criminal offense have the right to obtain the services of a legal representative to help in their defense.