Attacking Field Sobriety Tests at a DUI Trial

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When a motorist refuses to take a breathalyzer test, field sobriety tests are often a very important piece of evidence the State uses to prove a defendant guilty beyond a reasonable doubt of DUI. Judges rely on the police officer’s expertise in giving field sobriety tests, and the police officer’s subjective opinion based on the results of those tests that the defendant was under the influence of alcohol.

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The standard field sobriety tests that have been scientifically proven to show that a person’s blood alcohol level is .10 or greater are the walk and turn test, the one leg stand test, and the horizontal gaze nystagmus test. These tests have been validated through extensive research sponsored by the National Highway transportation Administrative (NTHSA) for effective DUI detection. When performed correctly, the horizontal gaze nystagmus test by itself it 77% accurate in DUI detection, the walk and turn test is 68% accurate, and the one leg state test is 65% accurate. By combining the horizontal gaze nystagmus and the walk and turn test, 80% accuracy can be achieved.

In order for these tests to have any validity, they MUST be administered in the prescribed, standardized manner according to NTHSA and the Illinois Supreme Court in People v. McKown, Docket No. 102372 (Ill. 2/19/2010). No exceptions, or else the tests are not valid. But often times the police officer does not possession the requisite expertise to evaluate these field sobriety tests correctly. Other times, the police officer cuts corners to save time and does not properly assess the motorist’s performance on this test. When this happens, you need to have an attorney who is familiar with the NTHSA requirements for validity of the tests on your side. A valuable DUI attorney can properly cross-examine the police officer and effectively persuade the judge that these tests should carry no weight with the court in making its decision of guilt because they were not administered properly.

Some examples of improper test conditions include, but are not limited to the following:

1. Did the police officer check for equal tracking of the pupils and pupil size before administering the horizontal gaze nystagmus test?
2. Was the motorist over 65 years old, did he/she have back leg or middle ear problems? Was the motorist wearing high heels during the test? These are all factors that could invalidate the tests.
3. Were the tests performed on the dry, hard, level, and non slippery surface?

While these points might seem minor during your DUI arrest, NTHSA says that these tests are NOT valid unless administered properly. Many police officers have not been trained in the administration of field sobriety tests since the police academy. They forget how to give these tests or get sloppy over the years. A person charged with DUI must have someone nitpicking the officer’s administration of the tests to the judge or jury. Whether you hire my firm to represent you or someone else, it is important that you have an advocate on your side that is familiar with NTSHA and the tests requirements.

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