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Are the standardized field sobriety tests reliable?

On Behalf of | Jun 13, 2023 | Criminal Defense

Field sobriety tests help establish probable cause when a law enforcement officer initiates a DUI arrest. The National Highway Traffic Safety Administration (NHTSA) standardized three of the most reliable tests. Rhode Island police officers who want to investigate a driver they suspect is driving while under the influence should have the training and competence to administer these tests. However, the tests are not free from administration and situational errors. They are not 100% reliable.

What are the standardized field sobriety tests?

The arresting officer must administer all three field sobriety tests to obtain a higher reliability percentage. Although because of the subjective nature of the tests, you can still challenge their capacity to validate a person’s level of impairment. The three tests are:

  • The Horizontal Gaze Nystagmus test (HGN): In this test, the arresting officer can ask you to follow an object with your eyes. When the driver follows the object to the side, the officer looks for involuntary eye jerking or nystagmus. The driver should be able to follow the object smoothly. The officer is the only person who can see and determine an involuntary jerking of the eye.
  • The Walk and Turn test (WAT): The test measures attention and balance. The officer will instruct the driver to take nine steps from the starting position. These must be heel-to-toe steps, meaning the left heel goes in front of the right heel and vice versa, in one straight line. The driver must turn around and repeat the process walking toward the starting position. The officer watches for eight observations, each demonstrating the driver’s ability to follow instructions and maintain balance.
  • The One-Leg Stand test (OLS): From the name itself, the test involves an officer asking a driver to stand and raise one leg. The foot should be pointing outward and approximately six inches off the ground. The officer then instructs the driver to count while the officer keeps a separate time of thirty seconds. The OLS is another test of balance and the ability to count aloud and follow instructions.

Even a person who is not intoxicated will find these tests difficult, especially under adverse weather conditions and extreme fatigue or stress. Getting arrested is a stressful experience. The driver might be too scared, tired or anxious to perform the tests effectively.

Challenging the administering officer

An arresting officer should have sufficient training and objectivity to administer these tests accurately. You could question whether they followed the standardized procedure. The evidence the prosecution has can significantly alter the driver’s life. It should be accurate.