How Accurate Are Field Sobriety Tests?

How Accurate Are Field Sobriety Tests?
Picture of an Officer administrating Field Sobriety Tests

Law enforcement agencies routinely use field sobriety tests to establish probable cause before they arrest drunk driving suspects. Given how widespread these tests are, you may assume that they are accurate. However, has shown that even the standardized tests are unreliable in measuring impairment. If you’ve been arrested for driving under the influence, you need to hire a DUI attorney in Atlanta. They may be able to challenge the results of the tests in court. In the meantime, let’s discuss the three standardized tests and some of the challenges with their accuracy.

The One-Leg Stand Test

If a police officer pulls you over because they suspect you’re impaired, they may administer the one-leg stand test. The officer will give you verbal instructions and then provide a demonstration. You will have to raise one leg and keep your foot parallel and around six inches off the ground. The officer will ask you to keep your hands at your side and count while looking at your foot. You must do this until they tell you to stop.

As you do this, the officer will look for the following clues:

  • Swaying
  • Hopping
  • Putting your foot down
  • Using your arms to give you balance

If the officer observes at least two of these clues, they will classify your BAC as above 0.10 percent.

Used on its own, the one-leg stand test is at best only 65 percent accurate. If you fail this test, you have good grounds for challenging the result. Furthermore, certain individuals are more likely to fail, and they shouldn’t be asked to perform the tests. This includes people who are overweight, those over the age of 65, and those who have problems with their legs, back or middle ear. If you fall into one of these categories, you need to tell your Atlanta DUI attorney.

The Walk-and-Turn Test

On your best day, you may find it difficult to walk in a perfectly straight line, pivot and do it again. However, a police officer can ask you to do just that after pulling you over. The officer will request that you stand heel to toe and keep your arms at your side. As you do that, they will give you instructions and provide a demonstration. You will have to take nine heel-to-toe steps forward on a line, then nine steps back. You must keep your arms at your side and watch your feet.

Officers are trained to look for several clues that suggest a BAC of 0.10 percent or higher. These include:

  • Problems balancing while listening to the instructions
  • Starting the test before the officer has finished giving the instructions
  • Stopping while walking
  • Not staying on the line
  • Using your arms for balance
  • Failing to walk heel to toe
  • Turning incorrectly
  • Take more or less than nine steps

According to the National Highway Traffic Safety Administration, the walk-and-turn test only has a 66 percent accuracy rate. However, if the officer observes just two of these clues, they can arrest you. There are many reasons why a person could fail including mental and physical impairment, unsuitable surfaces and external distractions. Your attorney may be able to challenge either the way the test was administered or the interpretation of the results.

The Horizontal Gaze Nystagmus Test

Nystagmus describes the unintentional jerking of the eyeballs. This jerking becomes more noticeable when an individual is impaired by alcohol and/or some drugs. Before administering the test, the officer will check your eyes for equal tracking, equal pupil size, and resting nystagmus. If you have any issues here, you may have an injury or a medical condition which makes the test unreliable.

Otherwise, the officer will go ahead with the test. This involves holding an object about 12 inches away from your nose and moving it slowly from side to side. You’ll need to follow the object with your eyes while keeping your head still.

The office will be watching each eye to see if:

  • Your eyes jerk or bounce
  • Nystagmus sets in before your eyes reach 45 degrees
  • Your eyes begin jerking within four seconds while you’re looking to the side

If the officer notices four or more clues, there’s a probable cost for arrest.

This test is the most accurate of the three but it’s still only 77 percent accurate. Several medical, physical and neurological conditions can cause nystagmus and police officers aren’t qualified to diagnose suspects. Therefore, the horizontal gaze nystagmus can also be challenged.

Contact Howard & Arca DUI Lawyers Today

As you can see, there are many problems with field sobriety tests. If you’ve been charged with a DUI, you need to consult a reliable criminal defense attorney immediately. We know all the complexities and we’ll work hard to ensure you are not unfairly disadvantaged. Contact us today to schedule a consultation.

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