Field Sobriety Tests (FST) are used by law enforcement to identify drunk drivers. During a DUI investigation, police may ask you to follow a set of simple instructions, such as standing on one leg or walking in a straight line. These tasks are simple for a sober person to complete, but difficult to execute under the influence of alcohol. According to the National Highway Traffic Safety Administration (NHTSA), there are three types of field sobriety testing:
- The One Leg Stand
- The Walk and Turn
- Horizontal Gaze Nystagmus
During the one leg stand, an officer will ask you to stand with your hands at your side and one foot raised several inches from the ground. Then, the officer will instruct you to count for thirty seconds. Failing the test may count as DUI evidence against you.
Like the one leg stand, the walk and turn test requires mental concentration and balance. During this test, the officer will instruct you to walk along a straight line, placing one foot in front of the other. After nine steps, you must turn and walk in the opposite direction.
The following actions could lead to a failed test:
- Stepping away from the line
- Taking the wrong amount of steps
- Using arms to balance
- Failing to follow instructions
The final test, the Horizontal Gaze Nystagmus, does not involve balance and coordination. During the test, an office will instruct you to look at an object as he / she moves it across your field of vision. If your eyes are unable to follow the object smoothly, law enforcement may assume that you are under the influence.