Q: How accurate are field sobriety tests?
A: DUI attorneys are always asked this question. The answer is that field sobriety tests are not entirely accurate. In fact, recently the Federal National Highway Traffic Safety Administration (NHTSA) conducted an evaluation of the three Standardized Field Sobriety Tests (SFSTs): the walk and turn, horizontal gaze nystagmus (HGN) and one leg stand. The results? The most effective test, the horizontal gaze nystagmus test, was only 78% accurate. In this test, an individual follows an object or light with their eyes and the officer looks for a side-to-side movement of your eyes, which is supposed to indicate intoxication. The one leg stand was determined to be 66% accurate and the walk and turn was determined to be 69% accurate in showing impairment.
DUI lawyers always look at where, when and how the tests were conducted, and by whom (which police officer or deputy sheriff). For example, there might be officers in the Roswell or Alpharetta or Johns Creek or Forsyth county or Cherokee county police departments who do the tests more skillfully than other officers in the same department. Also, a DUI attorney will know the roads of a city in North Fulton County, for example, or the roads in Forsyth county or Cherokee county and the DUI lawyer can ask appropriate questions about where and how the tests were conducted - questions like, was the road flat? were there lights that could impact the test? was a person just nervous? or on prescription drugs?