Field sobriety tests are physical coordination tests that are given if you are suspected of operating under the influence. The standard field sobriety tests are:
1. Horizontal gaze nystagmus;
2. 9-step walk-and-turn; and,
3. One-leg raise.

When used together there is some evidence that these tests can show that you are under the influence of alcohol. The police officer is watching your performance to decide if they should charge you with drunk driving.