Even when they eventually use a breath test to measure someone’s blood alcohol concentration, the police will often start with a field sobriety test just to determine if they think that driver is impaired. In fact, failure of a field sobriety test is enough to trigger an arrest on drunk driving allegations, even if someone has not been given a breath test.
As such, it’s important for drivers to know about the three main field sobriety tests that the police use, which they consider to be the most accurate.
The one-leg stand test
First off, you have the one-leg stand test when an individual will be told to raise one foot off of the ground for a predetermined amount of time. This will usually only take a few seconds, but the idea is simply to test their ability to hold their balance on one foot, as an impaired individual will likely not be able to do so.
The horizontal-gaze-nystagmus test
The HGN test measures the movement of the eye. The officer will look for jerky movements and will also be interested in how well the subject can track a moving object – like the tip of a finger.
The walk-and-turn test
Once again, the walk-and-turn test does measure someone’s balance and coordination, but it is also designed to measure their ability to follow instructions. For example, someone who forgets where they are supposed to turn around may be impaired because it should only take them a few seconds to reach that location. Compromised short-term memory can be a symptom of impairment.
If you are facing drunk driving charges after failing a field sobriety test, you must know about the defense options you have and the next steps to take.