Massachusetts DWI DUI OUI Field Sobriety Test Police Training Manual

OVERVIEW OF SFST
RESEARCH AND DEVELOPMENT

1. For many years law enforcement officers have utilized field sobriety tests to determine the impairment of a person’s driving due to alcohol influence. The performance of the person on those field sobriety tests was used by the officer to develop probable cause for arrest and as evidence in court. A wide variety of field sobriety tests existed and there was a need to develop a battery of standardized valid tests.

2. Beginning in late 1975, extensive scientific research studies were sponsored by NHTSA through a contract with the Southern California Research Institute (SCRI) to determine roadside field sobriety tests were the most accurate. SCRI published the following three reports:

• California: 1977 (Lab)
• California; 1981 (Lab and Field)
• Maryland, D.C., VA., N.C., 1983 (Field)

3. SCRI traveled to law enforcement agencies throughout the United States to select the most commonly used field sobriety tests. Six tests were used in the initial stages of this study.

4. Laboratory research indicated that three of these tests, when administered in a standardized manner, were a highly accurate and reliable battery of tests for distinguishing BACs above 0.10:

• Horizontal Gaze Nystagmus (HGN)
• Walk-and-Turn (WAT)
• One-Leg Stand (OLS)

5. NHTSA analyzed the laboratory test data and found:

• HGN, by itself, was 77% accurate
• WAT, by itself, was 68% accurate
• OLS, by itself, was 65% accurate
• By combining HGN and WAT an 80% accuracy can be achieved.

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