If the police pull you over on suspicion of drunk driving, one of the first things the officer may do is ask you to get out of the car and perform field sobriety tests. There are three different tests that they do measuring eye movement, balance, and ability to follow directions. These tests are supposed to indicate impairment to the officers, who can then make an arrest.
That being said, this is not the only way to measure impairment. Breathalyzers and similar devices can be used to check someone’s blood alcohol concentration and see if they are over the legal limit. Because of this, it has also been noted that field sobriety tests often get it wrong, and someone who fails a test could be arrested even though they would’ve passed a breath test.
Why does this happen?
There are a lot of reasons that this occurs, one of which is simply that the officer is deciding if you failed the test or not. Say that you trip on a rock and stumble during the walk-and-turn test. One officer may think that that isn’t a problem because you obviously just tripped in the dark. Another officer may say that you technically failed the test and so you’re going to be arrested. The same event happened, but it’s all up to the officer to decide what it means.
Additionally, these tests just measure your ability at the time, but the officer has no idea what your ability is like at any other time. If they decide that you are unable to balance, they may think you’re impaired, but maybe you just have a medical condition that makes balancing difficult.
You can see why it is so important to understand your legal options if you have been arrested on DUI charges.