You shouldn’t plan on having to pull over on the side of the road and run through a series of tests to prove you aren’t under the influence of drugs or alcohol. Rather, your best bet is simply planning a sober ride.

However, if you ever do find yourself at a DUI stop, it’s worth knowing some typical sobriety tests the police officer might ask you to perform and what they are hoping to reveal with these tests. Typically, suspects will have to complete a series of tests known as the standardized field sobriety test (SFST). They may also have to perform non-standardized tests.

According to the National Highway Traffic and Safety Administration, the SFST includes the following three components:

  1. One-leg stand: During the one-leg stand test, suspects must lift one foot at least six inches off the ground and count out loud until the police officer asks them to stop. Instead of starting at one, suspects must begin their count at one thousand. The officer will note any signs of the suspect losing balance.
  2. Horizontal gaze nystagmus: Through this test, officers will ask the suspect to follow a small object, like a pen, with their eyes. This is because when someone’s eyes are unable to follow an object with ease or seem to jerk involuntarily, this may indicate impairment.
  3. Walk-and-turn: In the walk-and-turn test, suspects take nine heel-to-toe steps in a straight line, pivot on one foot and take nine more heel-to-toe steps in the opposite direction. Like the one-leg stand, signs of imbalance may demonstrate impairment. Plus, not following the directions through taking too many steps or improperly turning may also signalize impairment.

If an officer determines that the suspect didn’t pass this series of tests with flying colors, then they might have the suspect take the breathalyzer test to get a read on their blood alcohol content level. They might also try more, not-so-standard tests. This might include having the suspect count the number of fingers an officer holds up, count backwards or say the alphabet.

There are a lot of notes an officer will make about a suspect’s performance on these tests and there are a lot of health and environmental conditions that can cause poor performance. So, if you have a DUI charge that doesn’t seem fair, then a criminal defense attorney can help you seek justice.