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How Important is the Sobriety Test?

The police use some quick tests in the field to establish probable cause for arrests when they suspect someone is driving impaired. People generally assume these tests are accurate. However, experimental research has shown that they have limited accuracy, although the accuracy improves if all the tests are correctly administered together.

Field Tests of Sobriety.

The sobriety test is the only court-approved measure of your blood alcohol level to be given in the field. It is true that individual police officers may vary from the standard and use tests of their own. The standardized “field sobriety tests” (FST) in Minnesota includes

  • The One Leg Stand (as a measure of balance).
  • The Horizontal Gaze Nystagmus test.
  • the Walk and Turn test.
  • a roadside or preliminary breath test (PBT), a hand-held breath test that measures alcohol level in the breath.

These tests are designed to help the police decide if you are impaired by alcohol when you drive. It is not illegal in Minnesota just to drink and drive. It just becomes illegal if your blood concentration level reaches the legal limit of .08 (8 parts per hundred liters of blood).

Research on the validity of these tests, their ability to detect high blood alcohol level shows that they are prone to error, especially if the officers are not well-trained in the standard administration of the test, or if the situation gets complicated in the field. One study found that officers tend to exaggerate the level of intoxication when administering the tests.

Studies found that an officer’s ability to assess blood alcohol level from the tests was about 47 percent when the tests were not performed according to strict standardization. Standardizing the tests, and if performed correctly, the horizontal gaze nystagmus test achieved a 77 percent accuracy. The walk and turn test achieved a 68 percent accuracy and the one-leg stand reached a 65 percent accuracy. When all three correctly administered tests were combined, officers could predict illegal blood alcohol 82 percent of the time. That means if the tests were correctly administered by the standardized method, they made errors nearly in nearly 1 in 5 people. In addition, there are many brands and models of breathalyzers. The roadside or portable breathalyzers have a margin of error between 15 percent and 23 percenter when used in the field.

In-House Tests of Blood Alcohol Level.

In Minnesota, when asked, you must agree to take the field tests. If you refuse, you will be arrested for an implied consent or a refusal to take a breath alcohol test as a crime. When they arrest you and any eventual evidence does not establish that you are above the limit, your DWI charge will be dismissed. If the officer can not factually prove you are above the limit the charge will be dismissed by the court. When you take the field sobriety test and if you are arrested on the basis of the officer’s probable cause, you will take the ultimate test once in the police station or a hospital facility. You will be given a blood test, a urine test, or a breath test once in police custody. You can consult an attorney before taking these medical tests.

Call a Minneapolis DWI Defense Attorney

Minnesota DWI law is complex. The facts in each case are different. The initial arrest is based on inexact instruments that rely on officer judgment. Yet the penalties are severe and can affect the rest of the life of the accused, even for a first offense. You should contact an attorney as soon as you are arrested. A qualified and experienced attorney can help you identify the irregularities in your case and advise you of your best course of action.

Judith Samson provides a 24-hour support and a free initial consultation. Our Minneapolis law office will have a knowledgeable criminal law attorney at your side when you need us. Please contact us to learn more.

Disclaimer: The information you obtain at this site is not, nor is it intended to be, legal advice. You should consult an attorney for advice regarding your individual situation. We invite you to contact us and welcome your calls, letters and electronic mail. Contacting us does not create an attorney-client relationship. Please do not send any confidential information to us until such time as an attorney-client relationship has been established.

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