FIELD SOBRIETY TESTS ACCURACY (p2)
In 1983, NHTSA conducted a study to determine the efficacy of the various field sobriety tests. Anderson et al., Field Evaluation of a Behavioral Test Battery for DWI (DOT HS-806-475, September 1983). The study found that "at present, the tests and procedures used vary between local agencies and officers" and that "for many of these tests, the relationship between performance and specific BAC levels has not been well documented." As a result of this and other studies, NHTSA now recommends only three field sobriety tests: walk-and-turn (walk-the-line), one-leg-stand, and nystagmus.
In 1986, another group of researchers tested the efficacy of the proposed standardized FSTs. The study, reported in Halperiri, Is the Driver Drunk? Oculomotor Sobriety Testing, 57 Journal of the American Optometer Association 654 (1986), involved testing the ability to determine whether a suspect's blood-alcohol level was above or below. 10 percent — that is, whether he was "under the influence" in most states. The test, conducted under laboratory conditions, indicated that the walk-and-turn tests resulted in a correct assessment 75.1 percent of the time, the one-leg-stand 75.5 percent, and nystagmus 81.8 percent; when all three were given, a correct determination was arrived at in 83.4 percent of the cases. Put another way, these "improved" FSTs still identify roughly one-fourth of innocent DUI suspects as guilty — and this presumes honest and accurate administration of the tests by an experienced officer under ideal laboratory conditions.
In 1987, many of the original researchers at the Southern Ohio Research Institute who had been federally funded to come up with a standardized battery published findings of their research. The study concluded that FSTs do not accurately measure driving impairment. In an article entitled Sobriety Tests for the Presence of Drugs, 3(1) Alcohol, Drugs and Driving 25 (1987), researchers recognized that such tests are designed to determine balance, steadiness, and reaction time but concluded that a connection between these factors and driving ability "is not apparent since neither a steady stance nor simple movement time is essential to the safe operation of a motor vehicle." While conceding that field sobriety tests may indicate the presence of alcohol, the researchers found that they do not necessarily measure driving ability.
In 1991, Dr. Spurgeon Cole of Clemson University conducted a study on the accuracy of FSTs. His staff videotaped 21 individuals performing six common field sobriety tests, then showed the tapes to 14 police officers and asked them to decide whether the suspects had "had too much to drink to drive." Unknown to the officers, the blood-alcohol concentration of each of the 21 subjects was .00 percent. The results: 46 percent of the time the officers gave their opinion that the subject was too inebriated to drive. In other words, the FSTs were hardly more accurate at predicting intoxication than flipping a coin. Cole & Nowaczyk, Field Sobriety Tests: Are They Designed for Failure?, 79 Perceptual and Motor Skills 99 (1994).
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