DWI Field Sobriety Tests

DWI Field Sobriety Tests

There are three Standardized Field Sobriety Tests in Texas. These tests were studied by the National Highway Traffic Safety Adminstration, or NHTSA. They conducted a series of studies designed to identify impaired drivers -- prior to chemical testing. In other words, the tests help an officer determine whether to continue a DWI investigation, and ultimately make an arrest.

The field sobriety tests were established in an attempt to gauge a person's divided attention with a series of physical and mental tasks. One of the goals of NHTSA was to standardize the field sobriety tests for use across the USA, which would allow for conclusions to be drawn from testing results. As such, there are currently three standardized Field Sobriety Tests in Texas, recommended by NHTSA:

  • One-Leg Stand
  • Walk-and-Turn
  • Horizontal Gaze

Problems with Field Sobriety Tests

Field sobriety tests have significant problems, some of which are actually address in the NHTSA literature. It's important to understand that you are not required to perform any of the Field Sobriety Tests, and there is no license suspension based on failure to do them. Of course, the officer will consider that a failure and take you to jail (please see DWI Refusals for more information on your rights and what you may refuse.)

These Things May Affect Your DWI Field Sobriety Tests

  • Past or current injuries to leg or knee;
  • Head Trauma or Injury (such as accident);
  • injuries to the back;
  • being overweight;
  • Age;
  • Fear, Anxiety, and Nervousness;
  • Inner-ear Problems;
  • lack of sleep;
  • Natural Lack of Coordination and Balance;
  • Shoes or Heels;
  • Location (Traffic, Uneven, Gravel/Dirt, Weather, Wind, Patrol Car Lights)

Texas Field Sobriety Tests

Horizontal Gaze Nystagmous (HGN) DWI Field Sobriety Test

Horizontal Gaze Nystagmous (HGN) is a test where officers have you follow their finger or a small object with your eyes. The officer looks for a small, involuntary jerking of the pupil when your gaze reaches the corners of your vision. Generally, your gaze is smooth as it flows left to right, but if there's alcohol in your system, the gaze becomes choppy as you scan left to right. Your pupil will slightly bounce. When an officer sees this bouncing, they will claim it's due to alcohol and you're impaired. They check for a lack of smooth pursuit by your eyes, distinct nystagmus at maximum deviation, and lastly the angle of onset of nystagmus prior to forty-five degrees.

Again, the problem here is that Horizontal Gaze Nystagmous (HGN) cannot tell you how much a person drank. If a person drank one beer, then you would expect HGN to be present. HGN does not increase or get worse if you had three beers as opposed to one. HGN can't tell you the number -- it can only say alcohol is in the system. So how does that help determine if a person is over .08%, or whether they have lost their mental/physical capabilities from alcohol


Walk and Turn Test DWI Field Sobriety Test

The Walk-and-Turn requires a person to walk nine heel-to-toe steps in a straight line, then turn and repeat the process. Before a person begins the Walk and Turn Test, the officer gives a detailed list of instruction, one after another. It's a long list of what to do, that most people could not recall, even sober.

It's always interesting to hear an officer say "well can you walk?" in response to a person claiming a past injury that might prevent stellar performance on an FST. The FSTs are not just "walking tests." These are tests that most people would have trouble performing stone-cold sober. They are much more than merely 'walking.'

Don't believe it? Here's the actual instructions an officer will say, provided by NHTSA, for a person to do the Walk and Turn Test:

"Put your left foot on the line. Put your right foot on the line ahead of the left foot, with the heel of your right foot touching the toe of your left foot. Place your arms at your sides and keep this position until I ask you to begin. Do not start to walk until I ask you to do so. Do you understand? When I ask you to start, take nine heel-to-toe steps down the line, turn around, and take nine heel-to-toe steps back. When you turn, keep your front foot on the line, and turn by taking a series of small steps with the other foot. While you are walking, keep your arms at your sides, watch your feet at all times, and count your steps out loud. Once you start walking, do not stop until you have completed the test. Count the first step from the heel-to-toe position as step one. Do you understand?"

One Leg Stand Test DWI Field Sobriety Test

The one leg stand has two parts: raising and holding your leg up, and counting to 30. Basically, the officer will instruct you to stand, with you feet together and arms at your side. Then, you raise one leg off the ground 6 inches high and count to 30 seconds. During the test, you need to keep your arms at your side and not use them for balance. Some officers will ask you to close your eyes, or tilt you head backwards, or other offshoots of non-standardized tests. During the test, the officer will note anything that is not correct, such as hopping, swaying, using arms for balance, placing your foot on the ground, or losing count.

As you can imagine, this test is not terribly easy for sober people, especially if you consider physical limitations of some participants (overweight, age, injuries), and take into account variances in the external influences (uneven or unpaved ground, crowded area with people watching, nervousness, poor light, police presence, etc...).


Non-Standard DWI Tests DWI Field Sobriety Tests

There are other tests that are not recommended by NHTSA, such as saying the alphabet backwards, counting backwards or by 2's, trivia, tilting your head back and balancing, and more. These tests have little to no correlation to impairment, which is why NHTSA decided to exclude them from their studies.

Closely Related Offenses

There are several types of DWI in Texas. A First Time DWI is the most common, but if a person has a prior DWI, then the charge is more serious. A DWI Second Offense is a Class A Misdemeanor and carries more severe penalties. Likewise, having two DWI priors means the next arrest will be considered a Felony DWI.

A first time DWI where the person has a breath or blood result .015% or higher, will have the DWI upgraded to a more serious DWI offense, specifically an Enhanced DWI (Class A).

Lastly, if there is no alcohol involved, or a combination of alcohol and a narcotic, then a person could be charged with a Drug DWI. This is true even if a person is taking legal prescriptions.

If you're looking for other offenses that are related to this one, you can see more information below, or click related legal offenses.




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