By Katherine North, Attorney at The Law Office of Randolph H. Wolf

Police officers commonly use roadside standard field sobriety tests (“SFSTs”) in DWI investigations to determine whether a driver is under the influence of alcohol. These tests usually consist of a series of three to five tests, such as the heel-to-toe, one-leg stand, horizontal gaze nystagmus (following a pencil with your eyes), finger-to-nose, alphabet recitation, the Rohmberg balance test (eyes-closed, modified position-of-attention), and so on.

These DWI tests have an aura of scientific credibility to juries. Unfortunately, however, they have no real basis in science. The conditions under which the field sobriety tests are taken almost guarantee failure. The instructions are long and complicated and the tests are usually given late at night, along a graveled or sloped roadside, with bright headlights from passing cars to a person who is nervous, frightened, and completely unfamiliar with the tests.

The Southern California Research Institute (“SCRI”), with a grant from the federal government, set out to find a standardized battery of DUI tests. Those three tests were the heel-to-toe, one-leg-stand, and nystagmus. After a study, however, even this company concluded that using the three standardized tests, 47% of the subjects tested would have been arrested for DUI even though they were under the then-0.10% limit. In 1981 the SCRI suddenly came up with better figures for the same tests: only 32% of those who failed the tests were actually innocent.

In 1991, a study on the accuracy of SFSTs was conducted at Clemson University. Individuals were videotaped performing six common field sobriety tests. The tapes were then shown the tapes to 14 police officers who were asked to decide whether the suspects were intoxicated or not. Unknown to the officers, the blood-alcohol concentration of each of the 21 subjects was 0.00%. Astoundingly, however, the officers concluded that 46% of these innocent people were intoxicated. In other words, the study found that field sobriety tests were hardly more accurate at detecting intoxication than flipping a coin.