If you are stopped and accused of drinking and driving, one of the questions you might have is if a field sobriety test is reliable. Field sobriety tests are used to establish probable cause for a DUI arrest, but these tests aren’t always 100% reliable.
Not all field sobriety tests are proven to be completely accurate. In fact, this is why multiple tests are often given during the same traffic stop.
How accurate are field sobriety tests?
The horizontal gaze nystagmus test, the HGN, is only around 77% accurate even when administered in an ideal scenario.
The test where people walk and turn around, also known as a heel-to-toe and pivot test, is also relatively inaccurate. It’s only approximately 66% accurate according to the National Highway Traffic Safety Administration.
The third test used most often is the one-leg stand. This test, when administered correctly, is only around 65% accurate.
As you can see from these statistics, there is no way that these tests can be accurate every time. There is a chance that the tests will be wrong, even when used during the same traffic stop.
What makes field sobriety tests inaccurate?
The reason that field sobriety tests can be inaccurate is there are so many unknown factors. For example, a person who has vertigo or other balance issues may fail a walk-and-turn test despite not having a drop of alcohol to drink. Someone with a neurological condition might fail the HGN test or be unable to balance during a flare of their condition.
The important thing to take away from this information is that field sobriety tests are fallible and are known to be inaccurate. Since they are not always accurate, they usually are not the only evidence that has to be collected during a traffic stop. Combined with a high blood alcohol content, it may make sense for a person to fail these tests and lead to a DUI, but even then, there is a chance that errors played a role in a false positive. This is why anyone who is accused of drunk driving needs to defend themselves.