Field sobriety tests are used to determine if a person is intoxicated or suffering from the influences of a medication or drug. If the individual is unable to drive due to intoxication, he or she could be arrested or charged with a crime.
Field sobriety tests, known as roadside tests, aren't the same as a Breathalyzer test, even though many people think they are all done together. These tests typically come before the breath test and are performed in a three-part series.
What happens during the three stages of a field sobriety test?
In the first section of the test, an officer may ask the individual to perform the horizontal gaze nystagmus test. When the officer holds up a pen and makes you follow it with your eyes, he or she is looking for involuntary jerking in the eye. This is exaggerated in people who are impaired by alcohol and some forms of drugs.
A one-leg stand may also be used. This is where a person is asked to stand on one leg with one foot off the ground. The person has to stand and balance for around 30 seconds. Losing your balance, swaying or using your arms to help you balance could be signs of intoxication.
Finally, the officer may ask you to complete a walk-and-turn test. This test requires you to walk heel-to-toe in a straight line. Then, you'll be asked to turn on one foot before walking back to the starting point.
If you fail any one of these tests, the officer may as for a breath sample to determine if you were driving behind the wheel while intoxicated.
Source: FindLaw, "Field Sobriety Tests," accessed Sep. 29, 2017