Posts Tagged ‘Field Sobriety Tests’

Minnesota DWI Field Sobriety Test Reliability

Sunday, January 15th, 2012

The field sobriety test in Minnesota or in any other part of the United States is one of the most controversial aspects of a DWI stop. The National Highway Traffic Safety Administration (NHTSA) developed a model system and published several training manuals for administering Standardized Field Sobriety Tests (SFSTs).  These tests are known as “divided attention tests” to determine the driver’s ability to perform mental and physical multitasking which is deemed a requirement for safe driving.

A police officer asks a person suspected for driving while impaired to submit to one or more SFSTs. The tests are conducted to help determine whether there is probable cause for a DWI arrest. If the person fails one ore more of the SFST tests often a DWI arrest is made. An individual who refuses to perform a SFST is usually simply arrested and must later submit to breath, urine or blood test.

Popular Minnesota Field Sobriety Tests

Below are some of the more popular Field Sobriety Tests used by Minnesota law enforcement.

Horizontal Gaze Nystagmus Test – Nystagmus refers to the jerking of an eyeball as it follows an introduced object. The administering officer observes the angle at which your eye starts to jerk while you keep your head still. A pencil or the officer’s finger, which should be 12-15 inches away from you, may be used as the object to follow with your eyes while your head isn’t moving. It is believed that if the eyeball jerks before 45 degrees, the driver’s BAC is 0.05.

Walk and Turn Test – Because intoxicated drivers find it difficult to perform tasks and listen to instructions simultaneously, this test requires you to do heel-to-toe movements on a dry, hard surface while following the officer’s instructions at the same time. During the test if the officer finds two or more signs (out of a possible 8 the officers are trained to look for) then you’re believed to have over 0.08 BAC level in your system. According to NHTSA, this test is 68% accurate.

One Leg Stand Test – In this test, the officer instructs you to perform a task while demonstrating the instructions to you. The officer also tells you not to start performing the test until you’re told to do so. To start the test, you have to stand with both heels together while your arms are down the sides. You are them asked to stand on one leg of your choice while holding your other foot out front approximately 6 inches off the ground for 30 seconds. If you struggle in this position, the officer assumes that your BAC is over 0.08.  Based on NHTSA study, this test is 65% accurate.

Alternative Not Scientifically Validated Tests

  • Modified-position-of-attention test
  • Finger-to-nose test
  • Reciting part of the alphabet
  • Finger count test
  • Counting numbers backwards test

Do Field Sobriety Tests Really Measure Impaired Driving?

The NHTSA standardized the field sobriety tests to ensure that police officers use scientifically-backed tests… but the FSTs become faulty when officers fail to properly conduct the tests, which is sometimes the case. The results of the tests also become worthless when the strict criteria of the NHTSA are not met during the administration of the tests. If any of the tests are improperly administered, then the validity of the FSTs is compromised.

Based on the manual published by the NHTSA, field sobriety tests are valid only when:

  1. The tests are administered in the prescribed and standardized manner;
  2. The proper clues are used to assess the driver’s performance; and
  3. The standardized criteria are employed to interpret the performance

If DWI Tests Were Properly Administered, is Failing the Tests an Indication of Impaired Driving?

Even when FSTs were correctly administered, failing the tests doesn’t necessarily indicate a person is guilty of impaired driving. Minnesota DWI lawyers know the assumption that a person with no alcohol in his/her system is coordinated enough to pass the tests is faulty. This is because there are several factors that can cause even a sober individual to become uncoordinated which include:

  • Illnesses
  • Stress
  • Fear of a police officer
  • Confusion
  • Fatigue
  • Age
  • Weight
  • Prescribed medication

Best Steps to Take When Charged with DWI in Minnesota

The nuances surrounding Field Sobriety Tests are complex and best left to an experienced Minnesota criminal defense attorney who focuses his or her practice on DWI defense.  An individuals performance on field sobriety testing is the foundation for a police officer’s determination whether there exists probable cause for an arrest.  Therefore, it is one of the first things a skilled attorney will review in determining if the arrest was lawful.


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