In order to detect whether a person is driving under the influence, the first step that police officers in Indiana and elsewhere usually take is to conduct a set of three standardized field sobriety tests. Although not fully accurate, these tests allow the apprehending officer to assess reasonably whether the driver's intoxication level is within the permissible blood alcohol concentration level of 0.08.
The first of those three standardized field sobriety tests is the "horizontal gaze nystagmus" test in which a DUI suspect is asked to follow the slow horizontal movement of an officer's pen or a flashlight while the officer observes the suspect's eyes for three signs of intoxication. This test is based on the premise that, beyond a BAC of 0.08, a person's eyes may jerk involuntarily even when asked to observe an object at low angles of deviation.
The second SFST is the "walk-and-turn" test. In this test, a suspect is asked to walk nine steps in a straight line, touching heel-to-toe, and then swivel around on one leg and return the same number of steps in that same straight line while the officer looks for at least two of eight intoxication signs. This test too is based on the premise that a person with BAC higher than 0.08 will fail this test.
The "one-leg stand" is the third SFST. For this test, a DUI suspect is made to stand for as much as 30 seconds with one foot held approximately six inches off the ground while counting off specific numbers. There are four designated signs of intoxication that an officer looks for when conducting this test. A person with a BAC higher than the permissible limit of 0.08 usually does not pass this test.
Indianapolis residents need to know that failing the SFST does not necessarily mean that a person is guilty of DUI. This is backed by the fact that validation studies conducted to determine the efficacy of these test found that none of these are 100 percent accurate. Therefore, if someone is apprehended under the suspicion of DUI, it may be a wise decision to contact a DUI attorney immediately.