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A Look at the Accuracy of Field Sobriety Tests

To better understand a driving under the influence charge and how to challenge it, we need to start at the beginning. So let’s take an in-depth look at how accurate field sobriety tests actually are along with how they influence DUI cases. The following is a look at standardized field sobriety tests, or SFSTs, which are commonly used in DUI cases in California.

Keep in mind that if a driver is unable to perform one or more of the standardized tests, an officer can administer a variety of other tests. These tests will accommodate for any disability a driver may have. Even if an officer believes a driver is under the influence of drugs instead of alcohol, he or she may still administer the standardized field sobriety tests.

There are three types of standardized field sobriety tests used. They are the walk-and-turn, horizontal gaze nystagmus and the one-leg stand. Here is an analysis of each test.
The Walk-and-Turn

The walk-and-turn has an accuracy rating of 79 percent. It is a sobriety test that divides a driver’s attention so that an officer can analyze his or her ability to listen and follow instructions. The driver is told to walk nine steps in a straight line. He or she must walk in a heel-to-toe manner. After the driver walks in one direction, he or she must walk in the opposite direction in the same manner. The officer studying the driver looks for:

  • The driver taking the wrong number of steps. For instance, instead of taking nine steps, he takes 12 steps.
  • He or she loses balance or has a hard time keeping balance.
  • The driver not being able to walk in a heel-to-toe motion.

One-Leg Stand

Studies have shown that this test is accurate 83 percent of the time. It is another type of divided attention test. The driver must stand on one foot with his other foot raised. Ideally, it should be about six inches from the ground. He or she must remain that way while counting out loud. The officer will observe the driver for about 30 seconds during this test. He or she is looking for:

  • Swaying.
  • The driver putting his or her foot down.
  • Lack of balance.

Horizontal Gaze Nystagmus

This field sobriety test has an 88 percent accuracy rate. Also, law enforcement considers the test the most accurate of all the field sobriety tests. With the Horizontal Gaze Nystagmus test, the driver must follow an object that an officer holds using only his or her eyes. The object is generally a penlight. The officer will look for a side-to-side movement in the eyes. This is a sign that the driver is intoxicated.

What the Accuracy Percentage Means to a DUI Case

Accuracy rates like the ones listed above may seem high. They may actually scare you if you are facing a DUI charge. However, the important thing to remember is that these results came from a study administered in connection with the National Highway Traffic and Safety Administration, or NHTSA. The NHTSA actually created and set the standardized field sobriety tests. The study does not take into consider the following issues:• What if the test was administered incorrectly?What if alcohol consumption had nothing to do with the driver falling the test?

  • What about the 12 to 17 percent of the time the tests are not accurate?
  • Was the driver wearing high-heeled shoes?
  • Were the tests conducted in a dangerous or distracting environment?

As you’ve read, the accuracy of the tests can yield a lot of strong defenses. To learn more, contact the Law Offices of Jonathan Franklin today.

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Jonathan Franklin DUI Attorney
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