Field sobriety tests are designed to mimic the multi-tasking and attention division that occurs while driving. According to the theory, if you can't successfully perform these tests, then you must be impaired.
This isn't always the case, however. Many people who haven't even had a drink then participate in these tests "fail" them. Before getting into why, let's take a quick look at what makes up the Standard Field Sobriety Tests.
You take three tests
Three tests make up the SFST. Below are short descriptions of each of them:
- The one-leg stand test requires you to maintain your balance on one foot for around 30 seconds or until the officer tells you to lower your other foot.
- The walk-and-turn test requires you to take a prescribed number of steps, heel to toe, in one direction, turn around and walk back in the same manner.
- Finally, the horizontal gaze nystagmus test measures the point at which your eyes begin to jerk as you look to one side using only your eyes. This happens to everyone, but when impaired, it happens sooner.
Just reading these brief descriptions, you may already see where these tests could go horribly wrong even when sober.
Why would a sober person fail these tests?
One problem with these tests arises from the fact that any number of physical and mental ailments and illnesses can affect the outcome. Another issues, perhaps greater than the first, is the subjectivity of the officer administering the tests. He or she already has a conscious or subconscious bias against you, so the tests may not go your way.
Yet another problem is the definition of "standard." The only way to ensure standardization across all tests would involve the officer reading the instructions to you and using the same scoring system for every driver. In reality, this just doesn't happen.
Do you have to participate in these tests?
Legally, you do not have to take these tests, but that won't stop the officer from trying to guilt, shame or intimidate you into it. He or she needs probable cause in order to arrest you, and the SFST help provide that. Not participating does not guarantee the officer won't arrest you if he or she believes enough probable cause exists without these tests.
More than likely, politely declining to participate in these tests would better suit your interests in the long run. However, in the short term, the officer will probably suspect you of hiding something and arrest you anyway. It will be the officer's responsibility to prove that enough probable cause existed, but it may take some time to sort out the situation. In the meantime, you may not have supplied the officer with an easy justification for his or her actions.