When you are pulled over and suspected of driving while intoxicated, you may be asked to perform/undergo a variety of field sobriety tests in Texas, including field sobriety texts and chemical tests.
The National Highway Traffic Safety Administration (NHTSA) has set out the guidelines for the three standardized field sobriety tests (SFSTs). The three tests are the Horizontal Gaze Nystagmus test (HGN), the Walk-and-Turn test (WAT), and the One Leg Stand test (OLS).
Horizontal Gaze Nystagmus
The Horizontal Gaze Nystagmus test is considered the most accurate of the field sobriety tests in Texas. This test is admissible to show some level of impairment. The officer will be looking for three separate specific clues in each eye; there are six total clues. If four or more clues are evident, the Horizontal Gaze Nystagmus test is allegedly 77% accurate in detecting a person with a blood alcohol level in excess of 0.10.
Nystagmus is defined as an involuntary jerking of the eyes. It is not something the person being tested will be aware of during the administration of the test. Involuntary jerking of the eyes will become more noticeable as a person’s blood alcohol level rises.
The second standardized field sobriety test is a divided attention test called the Walk-and-Turn test. Initially, the officer will have you assume a heel to toe position by instructing you to place your left foot on a line and place your right foot on the line with the heel of your right foot against the toe of your left foot. You will be told to keep your arms at your side and not to start the test until instructed to do so. The officer is to demonstrate this instructional stance while he is instructing you, the driver, how to stand. After these instructions are given, you will be asked if you understand the instructions so far. The officer will tell you after he gives the command to start, you are to take nine steps touching heel to toe, after the ninth step, turn, and then take nine heel to toe steps back. The officer is to demonstrate.
The eight clues the officer will be looking for are: you cannot keep your balance while listening to instructions; starting the test before instructed to begin; not touching your heel to your toe; stepping off the line; using your arms for balance; making an improper turn; and taking more or fewer than nine steps in either direction.
One Leg Stand
The third standardized field sobriety test is the One Leg Stand. This is also a divided attention task requiring you to process verbal instructions while completing physical exercises. The test requires a reasonably dry, hard, level, and non-slippery surface for the administration of the test. The officer will be looking for four different clues. If two or more clues are present or you fail to complete the test, the original research indicates there is a 65% chance you have a blood alcohol level over 0.10.
In a perfect setting, field sobriety tests may have some validity, but from the authors’ experience, their use in the field by officers is unfair to the drivers. They test normal abilities by having you perform abnormal exercises. The officer giving the test already thinks you are intoxicated –why else would he ask for the test? This officer who basically has his mind made up is the sole judge and interpreter of how you perform the tests. In Texas, these tests are strictly voluntary. As such, it is the authors’ opinion that a driver should never submit to any form of roadside sobriety testing. You don’t even have to say anything.
Remember that in almost every case the officer has no idea of how you would do on these three tests when completely sober.
In addition to the above field sobriety texts, you may be asked to take a breath test. Texas uses two machines, one called the Intoxilyzer 5000 Model 6800EN and the newer replacement machine called an Intoxilizer 9000. (Often called the “Intoxi-liar” because of its inaccuracies.) There are many factors that can cause these machines to report unfavorable results. Liver disease, chemicals, diabetes and other health conditions can cause the results to be inaccurate.
While blood testing is generally considered to be the most reliable and accurate method, breath testing is often used. Blood testing is the least desirable for the police because it is more expensive and time consuming. Additionally, blood testing would allow you to have a second test performed on your blood sample by your own expert.
Breath testing is more convenient, cheaper and is not subject to retesting. The machine is capable of preserving a sample. The law allows retesting of any saved sample but it costs about $2 to retain the sample and no agency is willing to spend the money or subject itself to being rechecked.
In addition to the inherent bias in the field sobriety tests, to be clear, the police use the cheapest, most convenient, non-testable, scientifically debated chemical test when your freedom is on the line.