At a traffic stop, police officers may use field sobriety tests to initially determine if a person was driving under the influence (DUI). However, these tests are not always accurate. What should people facing DUI charges know?
What forms of field sobriety tests might an officer ask you to perform?
The National Highway Traffic Safety Administration (NHTSA) has created specific procedures for three tests:
- Horizontal gaze nystagmus (HGN) test: In this test, the suspect follows an object with their eyes while an officer moves it horizontally while looking for involuntary eye movement.
- Walk-and-turn test: The suspect must walk nine steps heel-to-toe, turn on one foot and return along the same path.
- One-leg stand test: Here, the suspect stands on one foot about six inches off the ground and counts aloud until the officer says to stop.
Officers might also use non-standardized tests like touching their nose with a finger or counting backward. These tests check a person’s coordination, balance, and ability to handle tasks that require attention to more than one thing at a time, skills that drinking or drug use can weaken.
Are the results of these tests always accurate?
Field sobriety tests are common, but even the standardized tests are not 100 percent accurate. Studies have shown that the different field sobriety tests are between 79 and 88 percent accurate. This means that, depending on the test used, field sobriety tests may be inaccurate for one or two out of every ten people tested.
Many factors that have nothing to do with alcohol or drugs can affect the accuracy of field sobriety tests. For example, medical issues like inner ear problems, a person’s age or even simple nervousness can affect someone’s physical ability to perform the requested tasks.
The situation can also change a person’s ability to perform these physical tasks. Uneven ground, poor lighting or bad weather can negatively impact performance on sobriety tests. Restrictive clothing or inappropriate footwear can also hinder a person’s ability to successfully complete physical tasks.
Finally, the outcome of field sobriety tests depends heavily on the officer’s judgment. Different officers might make different calls on whether a suspect passes or fails a test. This introduces a significant level of subjectivity and can lead to inconsistent results.
Given these variables, the reliability of field sobriety tests can be questionable. If you face drunk driving charges based on these tests, an experienced defense attorney can help argue that external factors, rather than intoxication, may have influenced your performance.
Understanding the limitations of field sobriety tests and seeking experienced guidance can help you defend yourself against accusations of drunk driving and potentially reach a more favorable outcome in your case.