One of the tools that police officers have at their disposal when they’re trying to determine if a driver is too impaired to operate a vehicle is a field sobriety test. While there are many different options available, there are only three that are part of the standardized field sobriety test (SFST).
The SFST is endorsed by the National Highway Traffic Safety Administration (NHTSA) because when it’s administered in an acceptable manner, it’s considered accurate enough to be admissible in a court case related to impaired driving. Understanding the basics of these tests may be beneficial for anyone who’s stopped for suspected impaired driving.
One-leg stand
The one-leg stand requires the individual to stand with one foot off the ground while they count for 30 seconds. The foot that’s off the ground should be about six inches in the air. A person who’s impaired may put that foot down early or try to use their arms to balance.
Horizontal gaze nystagmus
The horizontal gaze nystagmus requires the person to follow an object side to side with only their eyes. For a sober person, the eye will move smoothly, but the movement becomes jerky if they’re impaired. This jerking gets worse when as the person looks away from the center of their visual field.
Walk and turn
The walk and turn requires the person to walk heel-to-toe in a straight line for nine steps then they turn around and return to the starting point in the same manner. This requires the person to count in their mind while they follow the instructions, so their attention is divided. People who aren’t impaired can do this without any issues.
Despite an endorsement of this broader testing strategy by the NHTSA, it’s still possible to call test administration and interpretation into question. If there’s any misinterpretation of the results of the test by the officer administering it, one or more components of this test might not be considered valid. This could have a negative impact on the prosecution’s case.
Working with a legal representative who’s familiar with these matters might be beneficial for individuals who want to include questioning SFST results in their defense, given the complexities of doing so and all that is at stake.