People who are pulled over for the suspicion of drunk driving may be asked to take a field sobriety test. While there are a host of tests available for law enforcement officers to use, there are only three that are part of the standardized field sobriety test (SFST).
The SFST is the only set of tests endorsed by the National Highway Traffic Safety Administration. It includes the one-leg stand, the horizontal gaze nystagmus and the walk and turn.
One-leg stand
The one-leg stand requires the driver to hold one foot approximately six inches off the ground for 30 seconds while they count. Indicators of impairment include putting their foot down, hopping, swaying or trying to balance using their arms.
Horizontal gaze nystagmus
The horizontal gaze nystagmus requires the driver to follow an object side-to-side using only their eyes. The officer watches for an abnormal jerking of the eyeballs while the person is tracking the object.
Walk and turn
The walk and turn requires the driver to walk in a straight line before turning to go back to where they started. While they’re walking heel-to-toe, they may exhibit several signs of impairment. Some of these include stopping to regain balance or losing their balance while turning.
While these tests can all provide snippets of information, the officer has to be able to put everything together to determine if the driver is impaired. The manner in which the test is conducted and the interpretation of the results may have an impact on the defense strategy a defendant facing drunk driving charges establishes.