160728-F-KC610-199
Staff Sgt. Quentin Humphries, 341st Security Forces Squadron installation patrolman, performs a horizontal gaze nystagmus as part of a three-part standardized field sobriety test July 28, 2016, at Malmstrom Air Force Base, Mont. The three tests included the horizontal gaze nystagmus, the walk-and-turn and the one-leg stand. (U.S. Air Force photo/Senior Airman Jaeda Tookes)