Background In Brazil, drivers are subject to arrest if they are found driving with a blood alcohol concentration (BAC) over 0.06%. At BACs between 0.02% and 0.06%, they have their driver's license withheld. The use of a field sobriety test would be an appropriate alternative in the absence of a breathalyzer or to test for other psychoactive substances. This study reflects the first experience with the Standardised Field Sobriety Test (SFST) in Brazil.

Aim To determine the accuracy of the application of the first Standardised Field Sobriety Test conducted in Brazil.

Method During police roadblocks, self-trained researchers applied the SFST on volunteer drivers (N=718), using the standardised 3-test battery (Horizontal-Gaze-Nystagmus, Walk-and-Turn, One-Leg Stand). A questionnaire on alcohol consumption and driver behaviour was conducted by researchers and the breathalyzer test was conducted by police officers (16.4% refused to perform it).

Results The breathalyzer test confirmed that of the drivers with BAC above 0.08%, 86% failed in the SFST, which resulted in 58% accuracy. However, considering the BAC limit in Brazil (0.06%), we have similar accuracy (57.9%): 70% of the drivers failed at least one of the standardised 3-test. These tests were conducted in two rounds, allowing researchers to hone their skills, which resulted in higher accuracy in the second round (65.1%).

Significance The SFSTs are valid tests that are feasible to use in field situations in Brazil, serving as indicators of the presence of alcohol or other substances. The use of the SFST as legal evidence could improve enforcement in Brazil.