Validation of the standardized field sobriety test battery at 0.08% blood alcohol concentration

Objective: A field study was conducted to evaluate the accuracy of the Standardized Field Sobriety Test (SFST) battery to assist officers in making arrest decisions at blood alcohol concentrations (BACs) below 0.10%. Background: The SFST Battery was validated at 0.10% BAC in 1981, but since then many states have reduced statutory limits for driving while intoxicated to 0.08% BAC. Methods: During routine patrols, participating officers followed study procedures in administering SFSTs, scoring results, making arrest/no arrest decisions, and completing a data collection form for each of the 297 motorists evaluated during the study period. The officers' final step in each case was the administration of an evidentiary breath alcohol test. Results: Overall, officers' decisions were correct in more than 91% of the cases at the 0.08% BAC level. Cohen's kappa tests found all officers' scores to be within the categories of substantial and near perfect agreement, indicating low variance among the officers and a high degree of interrater reliability. Conclusion: The results of this study provide evidence of the validity of the SFST Battery as an accurate and reliable decision aid for discriminating between BACs above and below 0.08%. Application: The SFST Battery presently is used by law enforcement officers throughout the United States to help make roadside arrest decisions for impaired driving.