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What Are Field Sobriety Tests?

Often, police officers in Nashville will use field sobriety tests as a precursor to a blood alcohol content (BAC) test, or a breathalyzer test. But just what are field sobriety tests, and what purpose do they hold in the overall process of potentially being arrested for driving while under the influence?

AAA DUI Justice Link defines standardized field sobriety tests (FST) as three different types of tests that officers perform to check whether you appear to be sober or not. If you fail any of the FSTs, it becomes possible for an officer to measure your BAC directly, which can lead to your arrest if your levels show that you are driving while over the legal limit. The three standardized FSTs include:

  • Following an object with your eyes as it is moved side to side (horizontal gaze nystagmus)
  • Standing on one leg 
  • Walking and turning

Within these categories, there are certain general estimates that are considered most appropriate. For example, in the walk-and-turn tests, you must generally walk about 9 steps and make sure that you touch your heel to your toe when taking steps forward. Balancing tests usually last for about 30 seconds, counting slowly, while an officer looks for potential signs of intoxication like hopping, putting your foot down, or swaying.

It should be noted that FSTs are not infallible and that there are other valid reasons that drivers may not be able to pass them, like physical disabilities or age. It should also be noted that some officers may employ non-standardized field sobriety tests. However, these are the most common and are what you're most likely to see if you're ever pulled over on suspicion of DUI.