Field Sobriety Tests (FSTs) are standardized tests used by law enforcement to determine if a driver is under the influence of alcohol or drugs. These tests include the Horizontal Gaze Nystagmus (HGN), Walk-and-Turn, and One-Leg Stand, which assess balance, coordination, and eye movement. While participation in these tests is voluntary in many jurisdictions, refusing to take them can lead to an arrest based on other observations, like the smell of alcohol or poor performance in non-standardized tests. The results of FSTs can be used in court as evidence of impairment, but they are not infallible, and individuals can challenge their validity with the help of legal representation. It's important for drivers to understand that while these tests help establish probable cause for arrest, they do not directly result in a DUI conviction; further chemical tests like breath, blood, or urine analysis typically follow.