Police officers who are trying to determine if a driver is impaired have specific methods that they commonly use to determine what’s going on. One of methods involves various field sobriety tests. With that said, not all tests are admissible in court.
The standardized field sobriety test is comprised of three tests endorsed by the National Highway Traffic Safety Administration. These tests are considered reliable enough to submit as evidence in a drunk driving case.
Horizontal gaze nystagmus test
The horizontal gaze nystagmus (HGN) test is one of the three standardized field sobriety test evaluations. In this test, an officer will ask the suspect to follow a moving object, usually a pen or a small flashlight, with their eyes. The object is moved horizontally from side to side in front of the suspect’s face. The individual is instructed to keep their head still and follow the object solely with their eyes, allowing the officer to observe the eye movements closely.
Walk-and-turn test
The walk-and-turn test is designed to assess a suspect’s ability to complete tasks that require both physical and cognitive ability. The suspect is instructed to take nine steps, heel-to-toe, along a straight line, turn on one foot and return in the same manner. This test can be conducted on any straight line; however, an actual line marked on the ground helps the suspect visualize their steps. Officers typically demonstrate the test to ensure the instructions are understood.
One-leg stand test
In the one-leg stand test, the suspect is required to stand with one foot approximately six inches off the ground and count aloud by thousands (one thousand-one, one thousand-two, etc.) until told to put the foot down. The officer times the subject for 30 seconds. The suspect must maintain balance while listening to and following the officer’s instructions.
The SFST must be conducted following very strict protocols. When there’s any deviation, the test’s results may be considered invalid. This is just one of the many reasons why anyone who’s facing impaired driving charges should work with a legal representative who can help them learn about their options for a defense strategy.