Common sobriety tests used during a DWI stop

When a police officer has reason to believe someone is driving under the influence of alcohol, they will likely flash their lights, throw on their sirens and conduct a traffic stop. From there, the suspect will probably have to run through a series of tests before coming face-to-face with a DWI charge.

A suspect’s performance on these tests will help the police officer see if their hunch that the suspect was drunk driving is accurate. Specifically, police departments across the country use a set of tests called the Standardized Field Sobriety Test or SFST.

These are the three components of the SFST:

  1. Walk-and-turn test: Through the walk-and-turn test, the suspect will have to take nine steps in a straight line while touching their heel to their toe with each step. Then, after nine steps they must use one foot to turn around and do another nine steps back to where they started the test.
  2. Horizontal gaze nystagmus test: During the horizontal gaze nystagmus test, the suspect must use their eyes to follow a small object that a police officer holds and moves around.
  3. One-leg stand test: While taking the one-leg stand test, the suspect stands in place, lifts one foot about six inches off the ground and counts out loud for 30 seconds. Instead of starting at one, the test-taker will begin counting from one thousand.

When suspects struggle to take these tests or don’t follow instructions, an officer may use their performance to provide probable cause for their arrest. For example, one common sign of impairment is loss of balance. This might involve the suspect flailing their arms during the walk-and-turn test or dropping their foot down too soon during the one-leg test.

It’s important to note that not passing these tests may have to do with causes outside of one’s control. Meaning the police officer may give unclear instructions, the side of the road may not be well-lit, or the suspect could have health condition that makes one or all these tests difficult.

Thankfully, if you ever need to fight a DWI charge, you don’t have to do it alone. Instead an experienced criminal law attorney can evaluate the circumstances of your arrest and choose an appropriate defense.