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How accurate are field sobriety tests?

On Behalf of | Dec 9, 2022 | Drunk Driving

A field sobriety test is a kind of evaluation that police use to determine if someone is driving under the influence of drugs or alcohol. These tests may be administered before a breath test to collect additional evidence. The following are several field sobriety tests often used:

  • Horizontal gaze nystagmus test: police may use this test to evaluate a suspect’s attention and to watch for any sudden eye movements
  • One-legged stand test: this test may check the suspect’s balance and direction-following abilities
  • Walk-and-turn test: the suspect may be inebriated if they fail to keep in a straight line or fail to follow instructions

Non-standardized field sobriety test: the above are considered standard tests, but police may use non-standard tests such as counting the alphabet backward or a finger-to-nose test

While these tests are commonly used by law enforcement, that doesn’t necessarily mean these tests are accurate. Factually speaking, the accuracy for an officer using field sobriety tests to determine the sobriety levels of a person suspected of drunk driving is about 77% – that still leaves a large gap for mistakes.

Why would a field sobriety test be inaccurate? Here’s what you should know:

Differentiating a drunk driver from a disabled driver isn’t easy

One of the key factors when determining if a driver is drunk is first knowing if they have any disabilities. A hidden disability can easily disrupt an officer’s judgment. 

Take for example a person who has a limp, they’d likely have difficulties walking a straight line or standing on one leg. Or, a person with a medical condition that affects their eyes may have trouble focusing during a gaze test. Inner ear problems, sinus infections and more can all interfere with someone’s ability to complete these tests properly.

When dealing with a suspected drunk driver, police should understand that there’s a possibility of human error during a sobriety test. However, when police charge someone with a DUI despite their disabilities, then the driver may need to know their legal options.