One thing many people do not realize is that the things they do and say prior to taking a field sobriety test can be equally as damaging as their performance on the test itself. Smelling alcohol on your breath is only one of many factors an arresting officer will consider. Something as simple as a request for your license and registration can be not only influential but consequential in the officer's decision to have you submit to a field sobriety test.
Another thing many people are unaware of is the extremely low standard for failure many of the tests have. People who are sure that they have passed a test because they walked a straight line or stayed on one foot are often surprised to find out they failed. Even worse is that the failure can be due to poor or ambiguous instructions on the part of the arresting officer. In short, many field sobriety tests are designed for you to fail them. In fact, as many as 1 in 3 sober people will often fail even the most accurate of tests.
Although there are many field sobriety tests an officer may employ, the NHSTA has only authorized three of them: the walk in a straight line test, the stand on one leg test, and the horizontal gaze nystagmus.
Horizontal Gaze Nystagmus
This test, when conducted correctly, is the most accurate of all field sobriety tests. However, the devil is in the detail. First of all, like every test, some people are unable to pass it regardless of their toxicity level. Roughly 1 in 4 people can never pass it, no matter how correctly it is performed, and no matter how sober they are.
Further, some courts are extremely skeptical of it. In Kansas, the courts have been extremely reluctant to rely on the horizontal gaze nystagmus test.
Finally, and perhaps most importantly, the test is extremely difficult to administer correctly. Police officers are not optometrists, and really, are unable to adequately explain the behavior of one's eye muscles: they merely employ the test as they are trained to do. Also, many move their hands too quickly or slowly, compromising the test's validity. Many others fail to keep the correct distance or hold the object at eye level. The result is a suspect test result.
Stand on One Leg
The easiest to administer, and the most difficult to perform, it is accurate on only about 3 in 5 people. Standing on one leg for 30 seconds without wavering, using your hands for balance, hopping, or putting your foot down is difficult for a lot of people who are not only sober, but in good physical condition.
Walk a Straight Line
This test, when conducted correctly, is still failed by roughly one third of all people, regardless of their alcohol intake. Its biggest drawback is that the conditions for performing it are often substandard. The driver often lacks a straight line on a level, well-lit, dry, solid surface on which to walk. Making the test more difficult are the many instructions it requires, combined with the fact that they are often given ambiguously or erroneously by the officer. The result of this plethora of commands is that even perfectly sober people can forget to mind them. Another big problem with the test is that there are often distractions (flashing lights, noises, passing cars, and sometimes the officer himself) which can compromise the test's validity.
The Breathalyzer
Most states, including Kansas and Missouri, use two different tests, the first a preliminary breath test (PBT), and the second one a more official test.
There are several machines which have been authorized for use, including the Intoxilyzer 5000 and the Intoxilyzer 8000. Each has a very strict set of instructions which must be followed, and a failure to do so can vastly compromise the validity of your test. The Law Office of Phillip Murphy is familiar with the instruction manuals for each of the breathalyzer machines, and will ensure that your test was performed correctly.