The DUI field is full of psuedo-science. When I say that, I mean that there are many elements of a DUI prosecution case that sounds scientific, when in fact it is not, because it has not been reviewed or conceived using the proper scientific methods to ensure reliability and validity.
One such aspect is what is called “standardized field sobriety testing.” You know, standing on one leg or touching your finger to your nose. Or repeating the alphabet from G to T. Or picking up coins from the ground.
If these tests were in fact scientific, we would know the answers to the following questions: Do intoxicated people test differently, under the same testing conditions, from people who are sober? Can these results be replicated if the same people are tested by different officers?
In fact, there has been very little research in this area. We don’t know the answers to these questions. Many field tests were created by police officers on the road and have been passed down over the years from one generation to the next as if they had some validity. Only three field tests have been approved by the NHTSA for DUI detection: the one leg stand, the walk and turn and the horizontal gaze nystagmus. But even those three tests have not been properly vetted, and they have large margins of error.
In addition, officers are typically trained in field sobriety testing during a one week long crash course in it, and they only get occasional refresher courses, if at all. Once they are out on the road, their testing methods are not reviewed for quality control to ensure that they are being administered properly. It is not unusual for officers to start changing the tests to add their own personal twists when these are supposed to be standardized tests.