Field sobriety test accuracy FAQ

There are numerous ways a sober person might be accused of drunk driving after a field sobriety test, including trouble balancing or nervousness.

Field sobriety tests are commonly conducted by police officers in Colorado and elsewhere during traffic stops when drunk driving is suspected. However, certain factors may mean that these tests are not as accurate as chemical tests.

What is a field sobriety test?

The field sobriety test, according to the National Highway Traffic Safety Administration, consists of three different tests, and relies on an officer's individual interpretation. They include the walk-and-turn test and the one-leg stand, which measure a driver's understanding of directions, balance and walking ability. During the horizontal gaze nystagmus test, an officer will watch the involuntary movements of the subject's eyes, which are often more pronounced after drinking.

How can sober drivers fail the field sobriety test?

However, failing any of these tests does not necessarily mean the person was driving while intoxicated. According to ABC Action News, some physical or mental conditions may lead an officer to falsely believe the person had been drinking. These may include the following:

• Natural problems with balancing or inner ear conditions

• Injuries, illnesses or physical restrictions that affect walking

• Speech impediments or cognitive conditions that may mimic signs of intoxication

Additionally, if a driver feels extremely nervous or intimidated when asked to do a field sobriety test, he or she might perform poorly and end up being accused of a crime.

Are field sobriety tests more accurate than not?

Despite the numerous ways a sober driver might fail a field sobriety test, many people might believe these tests are still quite accurate. According to NBC 29 News, however, studies have suggested the opposite. The horizontal gaze nystagmus test has been shown to be 77 percent accurate, the walk-and-turn test 68 percent accurate and the one-leg stand accurate only 65 percent of the time.

To illustrate the potential difficulties of passing a field sobriety test, three people at a shopping center were asked to perform the test while sober. Two of them experienced difficulties balancing, despite one of them claiming he had good balance. One person said she had difficulty understanding the directions of the test because she was sleep-deprived. All of the subjects said that the tests could be more difficult to perform under real conditions, especially if they were nervous.

If you were accused of drunk driving, you may find it beneficial to speak with a DUI defense attorney in Boulder. An attorney can discuss with you the circumstances that led to your arrest and answer the questions you have about your case.