Field sobriety tests determine driver impairment. The purpose behind a field sobriety test, according to AAA, is to assess your coordination and balance and to determine sobriety. These results are admissible in court. While the tests are difficult to pass if intoxicated, there are reasons why you may fail the test without touching a drink.

The Standard Field Sobriety Test includes three different tests. An officer may ask you to perform all three, including the horizontal gaze nystagmus, during which you balance on one leg, and a walk-and-turn style test.

Types of tests

The HGN is a reflexive jerk of your eye. While this happens to everyone when you rotate your eyes at high peripheral angles, it is more exaggerated when you are drunk.

The one-legged stand involves standing with one foot six inches off the ground. Then the person must count until the officer asks him or her to put the foot down. If the officer sees you sway, use your arms to balance, hop to balance or put your foot down, he or she may decide you are under the influence.

Walk-and-turn is the other test. This one involves walking nine steps in a straight line, heel-to-toe. Then, you turn on one foot and return in the opposite direction. If you cannot listen to instructions or cannot perform the walk without using your arms to balance, this is a failure.

Reasons drivers fail

Drivers do not always fail due to drunkenness, however. Some people have medical problems that make balance difficult. Some may have injuries that make it difficult to stand on one foot. It is crucial to alert officers to medical issues that inhibit the test.