Reliability of DUI Field Sobriety Tests

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In most of the United States, field sobriety tests or FSTs are among the most controversial elements of a DUI/DWI stop.

The NHTSA or National Highway Traffic Safety Administration has created a model system and has published a number of training manuals on how to properly administer SFSTs or standardized field sobriety tests. Also known as “divided attention tests,” these tests were created to determine a driver’s ability to perform physical and mental multitasking, which is considered a requirement for safe driving.

A police officer asks an individual suspected for impaired driving to perform one or more SFSTs in order to determine whether there is probable cause for a DUI/DWI arrest. Should the person fail one or more of the tests, a DUI arrest is likely to be made. Should the individual refuse to perform the SFST, he may simply be arrested and should later submit to a urine, blood or breath test.

Popular FSTs

Here are some of the more common field sobriety tests used by law enforcement officials:

·        Walk-and-Turn Test – Intoxicated or impaired drivers have difficulty listening to instructions and performing tasks at the same time. The Walk-and-Turn test requires an individual to do heel-to-toe movements while simultaneously following the police officer’s instructions. Officers are trained to look for eight signs of impairment. If the officer identifies two or more signs, then the driver is believed to have a BAC level exceeding 0.08. Based on studies by the NHTSA, the Walk-and-Turn test is 68% accurate.

·        One Leg Stand Test – During this test, the driver will first stand with both feet together with arms at his sides. He will then be asked to stand on a leg of his choice for 30 seconds, holding his other foot out roughly 6 inches off the ground. Should the driver struggle in this position, the officer may assume that his blood alcohol content level exceeds 0.08. Studies by the NHTSA show that this test is 65% accurate.

·        Horizontal Gaze Nystagmus Test – The nystagmus refers to the jerking movement of the eyeball as it follows a specific object. The officer will hold a pencil or his finger about 12 to 15 inches in front of the driver’s face, and the driver will be instructed to follow the object with his eyes while keeping his head still. The administering police officer observes the angle that the eye begins to jerk while the driver keeps his head completely still. Should the eyeball jerk before it reaches a 45-degree angle, the driver’s blood alcohol content level is likely 0.05.

Alternative Tests

The following tests are alternatives to those mentioned above, but are not scientifically validated.

·        Finger-to-nose test

·        Finger count test

·        Modified-position-of-attention test

·        Reciting specific parts of the alphabet

·        Counting numbers backwards

Measuring Impaired Driving

The NHTSA has standardized the field sobriety tests in order to ensure that all police officers use tests that are scientifically backed. Of course, these tests become faulty once officers fail to conduct these tests properly.

Test results also become insignificant once the strict criteria of the NHTSA are not met during the administration of these tests. Should any of the tests be administered improperly, the validity of these tests is deemed compromised.

Based on the NHTSA’s published manual, field sobriety tests are considered valid when:

·        They are administered in a standardized and prescribed manner

·        Proper clues are used in assessing a driver’s performance

·        Standardized criteria are employed to interpret the driver’s performance

When a driver fails a FST, it doesn’t necessary mean that the test was incorrectly administered or that the person is guilty of impaired driving. Minnesota DWI attorneys understand that there are several factors that can cause a sober individual to appear uncoordinated. These factors are:

·        Age

·        Weight

·        Stress

·        Illnesses

·        Confusion

·        Fatigue

·        Fear of a police officer

·        Prescribed medication

Hiring a DUI Attorney

An individual’s performance on a field sobriety test is the foundation of an officer’s determination of whether a probable cause for an arrest exists. The subject of field sobriety tests can be complex to deal with, and it is best to leave a case in the hands of a professional criminal defense attorney.

 

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