The simple answer to this question is that they are definitely not accurate. Even the creators of the standard field sobriety tests — the one-leg stand test, the walk-and-turn test, and the horizontal gaze nystagmus test — admit they are not 100% effective at identifying drunk drivers. In fact, they are not even in the high 90s percentage wise. The next question would then be why to police rely on them so much?
Law enforcement officers rely on field sobriety tests because they often provide an easy way to establish probable cause for a DUI arrest. They help provide an easy avenue because even around one-third of sober people fail them. Yes, that is correct. Even people who have not had a drop of alcohol can fail these tests and end up under arrest.
This may surprise many people and make them think twice about participating. The problem is even though they may not want to take these tests, they may think they are legally obligated to do so. The good news is that is untrue. People who do not participate in these tests are not violating the law. However, police officers will often attempt to guilt, shame or intimidate people into doing so.
If an individual who is fairly certain he or she should not have failed field sobriety tests ends up under arrest, they have the right to challenge the results. These tests are highly subjective since they rely on the officer’s interpretation of the individual’s performance. The law may provide guidelines, but ultimately, each officer makes the final call. For this reason alone, people should respectfully and calmly decline to participate. They could still end up under arrest, but at least they did not help the officer further establish probable cause for the arrest.