A field sobriety test (FST) is a standardized test that police officers across the country are trained to administer to drivers that they suspect are under the influence of alcohol. The three most common FST’s are the one-leg stand (balancing on one leg for a period of time, without the use of arms for balance), the walk-and-turn test (walking on a straight line using heel-to-toe- steps), and the horizontal gaze nystagmus (HGN).