Study shows inaccuracy of FSTs. Field sobriety tests are given by California DUI cops, including:
horizontal gaze nystagmus test, which involves following an object with the eyes (such as a pen) to determine characteristic eye movement reaction.
walk-and-turn (heel-to-toe in a straight line).
modified-position-of-attention (feet together, head back, eyes closed for thirty seconds; also known as the Romberg test).
finger-to-nose (tip head back, eyes closed, touch the tip of nose with tip of index finger).
recite all or part of the alphabet (a common myth is that the alphabet must be recited backwards, however, this is never done during an FST, as many sober people are unable to do this.).
touch each finger of hand to thumb counting with each touch (1, 2, 3, 4, 4, 3, 2, 1).
count backwards from a number such as 30 or 100.
breathe into a "portable or preliminary breath tester" or PBT.
Although most California DUI law enforcement agencies continue to use a variety of these FSTs, increasingly a 3-test battery of standardized field sobriety tests (SFSTs) is being adopted. These tests are recommended by the National Highway Traffic Safety Administration (NHTSA) after studies indicated other FSTs were relatively unreliable. The NHTSA-approved battery of tests consists of the horizontal gaze nystagmus test, the walk-and-turn test, and the one-leg-stand.
DUI testing studies question whether the tests increase the officer's ability to judge. In 1991, Dr. Spurgeon Cole of Clemson University conducted a study on the accuracy of FSTs. His staff videotaped 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 and drive". The blood-alcohol concentration of each of the 21 DUI subjects was .00, unknown to the officers. The result: the officers gave their opinion that 46% of these innocent people were too drunk to be able to drive. This study showed the possible inaccuracy of FSTs.
Source: Cole and Nowaczyk, "Field Sobriety Tests: Are they Designed for Failure?", 79 Perceptual and Motor Skills Journal 99 (1994)