This paper presents some results of a three-year investigation of the reliability and validity of field sobriety tests. The three-part standardised field sobriety test (SFST) battery was used, consisting of: (1) walk-and-turn (WAT); (2) one-leg stand (OLS); (3) horizontal gaze nystagmus (HGN). In the first year, 1990, only weak statistical associations were found between drivers' blood alcohol concentrations (BACs) and their SFST performance. To examine possible explanations of these unexpected results, a special study was made during 1991 of the validity and reliability of all three SFSTs as BAC predictors. It was combined with the normal roadside sessions on five consecutive weekends, on the assumption that experts' performance in field settings would approximate the tests' fundamental validity. Inatter help to assess the longer-term effects of training on the reliability and validity of SFSTs. It concentrates on test validity. 361 drivers and 119 dosed subjects participated in the study. As the results at best offer mixed reviews of the effectiveness of the SFSTs, several alternative strategies are proposed for future sobriety studies.
Abstract