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What You Need to Know about Field Sobriety Tests

Posted on in Operating While Under the Influence

Wisconsin defense attorney, Wisconsin criminal lawyer, Milwaukee drunk driving attorneyIf you are pulled over and the police suspect you are operating your vehicle under the influence of alcohol, you will likely be asked to perform field sobriety tests. The three tests most commonly used by law enforcement in Wisconsin and nationwide to determine if you are operating your vehicle while intoxicated (OWI), in order of reliability are; the horizontal gaze nystagmus, the walk and turn, and the one leg stand. If administered properly, each test can help law enforcement determine if a driver is under the influence of alcohol or other drugs,.

The Horizontal Gaze Nystagmus (HGN)

An HGN test is the most accurate of all of the field sobriety tests, with a 77 percent accuracy rate in detecting high blood alcohol content (BAC). Nystagmus means involuntary jerking or bouncing of the eyeball, with pupils appearing to be pulled back towards the center of the eye. This can be caused by several things, most notably alcohol use. It can also happen as a result of certain drugs that depress the central nervous system. The higher the concentration of blood or alcohol in the blood, the more noticeable the nystagmus is.

This test is administered by using a pen or a finger held about 12 inches from the driver’s face. The officer will move the pen or finger from one side to the other while observing the driver’s eye movements. Any eye jerking before a 45-degree angle is reached indicates the possibility of a BAC higher than .5 percent.

It is important to remember the police are not medical professionals, and often administer the test improperly.  This can result in flawed test results.

The Walk and Turn Test

If a walk and turn test is properly administered, it is also very accurate in predicting high BAC contents (just under 70 percent). This is a simple, two-part test.

This test is administered by instructing the driver to stand with one foot in front of the other. This is a heel to toe position, in a straight line. If this initial instruction is not followed properly, it is the first sign the driver may be under the influence of alcohol or other drugs. The police officer will then demonstrate how to walk heel to toe in a straight line, and the driver will be instructed to take nine such steps in a straight line, then turn around and do the same thing. While doing this, the driver must count the steps out loud.

Obviously starting prematurely or not following the heel to toe instructions are signs of intoxication. The inability to remain balanced, stepping off the line, using arms to stay balanced, taking the wrong number of steps, or making an improper turn are additional signs of intoxication that the police are looking for during this test.

The walk and turn test is often conducted improperly, as it must be performed on a dry and level area. Also, high heels can interfere with the test. For these and other reasons, the police often make errors in conducting this test that can lead to your arrest.

The One-Leg Stand Test

The third of the standardized field sobriety tests used nationwide is the one-leg stand test. The one-leg stand test has the lowest accuracy level of the three – even when administered properly, it only provides 65 percent accuracy of BAC over .10 percent.

The test is quite simple – the police officer will tell the driver to stand with their feet together and their arms at their sides, and then he will ask the driver to raise one leg about six inches off the ground. While that leg is lifted, the driver will be told to start counting aloud, beginning at one thousand.

While taking the test, the police are looking to see if a driver needs to use their arms to keep balance, if the driver hops on the one foot they are standing on to maintain balance, or drops the raised foot to the ground. Any of these can be clues of intoxication. Again, if the test is not performed on a level, dry surface, it is not properly administered, and high heels can also interfere with this test. Like the walk and turn test, this test is often performed under improper circumstances.

What Happens after the Field Sobriety Tests?

If the police have decided to administer these tests, they likely already think you are intoxicated and plan to arrest you. However, if you perform well, you may be sent on your way. If you fail any of the tests, the police will ask you to take a breathalyzer test, and if you blow higher than a 0.8 you will be arrested for OWI.

Our experienced Milwaukee OWI defense attorneys are ready to help you if you were arrested after “failing” a field sobriety test. We will do everything possible to keep your case out of the courtroom entirely, and have your charges lowered or dismissed if possible. Our attorneys stand ready to defend you vigorously, and you must act very quickly if you are arrested for OWI, so call us at 414-271-1440 or send us an e-mail today.



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