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Sobriety tests aren't always right: Here's why

If you're stopped by the authorities, they may state that they want you to take a field sobriety test, especially if you take a Breathalyzer test and have a blood alcohol content that is close to .08%. The goal of field sobriety testing is to see if you're impaired or able to drive safely.

Field sobriety tests have been used for decades, but in the 1970s, the National Highway Traffic Safety Administration did ask for the evaluation of these tests to see if they were accurate. The institute that performed the research, the Southern California Research Institute, recommended three field sobriety tests that were the most accurate:

  • One-leg stand
  • Walk and turn
  • Horizontal gaze nystagmus

The trouble with these tests is that there is room for human error. The NHTSA knew that the officers had an error rate of a shocking 47%. It went on to ask the SCRI to standardize testing, so the error rate would be reduced. Doing this, each has a better accuracy rate, but they are by no means flawless. In fact:

  • Walk-and-turn tests have an accuracy rate of only 68%
  • Horizontal gaze nystagmus testing has an accuracy rate of only 77%
  • One-leg stand tests have accuracy rates of only 65%

On average, the tests, when used together, are 85% accurate. That means 15 out of 100 people who take the test will be falsely accused of intoxication or impairment.

Why are field sobriety tests used if they aren't accurate?

A field sobriety test, combined with other tests, may be more accurate. For instance, if your BAC is .07% and you fail all three tests, then the officer would have evidence of your impairment and be able to arrest you. However, field sobriety tests aren't a scientifically proven method, so your attorney will still have an opportunity to question the results.

If your BAC was below .08%, the officer needed more information to try to arrest you for a DUI or for driving while impaired, which is why they chose to use one or more field sobriety tests. The trouble is that many people can't perform these tests, even when they're sober. Someone with balance issues, neurological problems, or other illnesses or disabilities, may not be able to complete one or more field sobriety tests regardless of their level of intoxication.

Attorneys know that field sobriety tests aren't always accurate, and they'll use this to fight any DUI charges made based on them.

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