What is the primary purpose of the Standardized Field Sobriety Tests?

The primary purpose of Standardized Field Sobriety Tests (SFST) is to assess a driver's level of impairment due to alcohol or drugs, which is closely related to determining Blood Alcohol Concentration (BAC) levels. SFSTs are designed to provide a law enforcement officer with observable and measurable evidence of impairment that correlates with BAC levels without the use of breathalyzers or blood tests. These tests include tasks that test balance, coordination, and cognitive function, which are all affected by alcohol consumption.

While assessing a driver's mental state could be considered a secondary benefit of SFSTs, the tests are not specifically designed to evaluate driving experience or vehicle condition, nor do they measure BAC directly. Instead, they allow officers to make an informed decision about whether a driver is impaired based on their performance during the tests, thereby providing a critical step toward determining the driver's BAC through subsequent testing if necessary.