Michigan drivers may have heard about field sobriety testing, but they may not know what this testing actually entails or what officers are looking for. The Standardized Field Sobriety Test is a combination of three different standardized tests that can be used to give an officer probable cause for arrest. The three tests include the horizontal gaze nystagmus, or HGN, the one-leg stand and the walk-and-turn.
Under normal circumstances, a person’s eyes will involuntarily jerk when rotated at a certain angle. When a person is under the influence of alcohol, however, the eyes will jerk more dramatically and at lesser angles. As a result, they may have trouble smoothly tracking an object. With HGN testing, officers look to see if the eye can follow an object smoothly, if the jerking is distinct and if the jerking occurs within 45 degrees of the center.
In the one-leg stand test, the person must stand on one leg while counting by thousands for 30 seconds. Swaying, balance checking using the arms, hopping or putting the foot down may indicate impairment. For the walk-and-turn test, the person must walk heel-to-toe for nine steps one way, turn and then walk another nine steps in the same manner. Indicators that the person might be impaired include beginning before the officer completes the instructions, losing balance, stopping in order to regain balance and taking too many or too few steps.
While field sobriety tests are popular methods of testing for impairment, some people may not be capable of passing the tests because of illness or physical impairments. If someone was taken into custody and accused of drinking and driving after being unable to complete the field sobriety tests because of such reasons, an attorney may provide strong representation for their client. No information in this article should be construed as specific legal advice.
Source: National Highway Traffic Safety Administration, “The Highway Safety Desk Book”, November 22, 2014