What field sobriety tests are used by police?

Of the three field sobriety tests standardized for use by the National Highway Traffic Safety Administration, none are completely accurate.

Anyone in Minnesota who has been stopped by officers and asked to participate in testing to determine potential intoxication knows that this can be a very intimidating experience. Law enforcement officers often demand that a driver submit to a variety of tests before using a breath test device or blood test to measure actual alcohol levels.

These other tests are commonly referred to as field sobriety tests. While a breath test, blood test or urine test may provide a chemical reading showing the amount of alcohol in a person's body, field sobriety tests cannot tell whether or not a person is intoxicated or how intoxicated they might be.

Instead, FieldSobrietyTests.org explains that this battery of tests is designed only to support the fact that a driver might possibly be intoxicated. The results of these tests are then used to support arresting the person for drunk driving. Unfortunately, they are often admitted as reliable evidence in a trial or driver's license hearing, despite their shortcomings. For that reason, drivers should understand what these tests are and what they are not. In addition, driver's should understand that they are under NO LEGAL OBLIGATION to perform them.

Three approved tests, none fully accurate

The National Highway Traffic Safety Administration has approved three tests for use during these investigations. Each has a different level of accuracy and none are even close to 100-percent accurate.

The walk-and-turn test requires that a driver walk in a heel-to-toe fashion along an imaginary line. After taking nine steps, they are expected to turn and return in the same manner to their original position. There are a number of what the police refer to as "clues of impairment" on this test, but they are not revealed to the test subject in advance of the "test." This test is said to be accurate 68 percent of the time. It is important to remember that using a coin toss would get the right answer 50 percent of the time, so this so-called test is only slightly more reliable than that.

The one-leg stand test requires a driver to balance perfectly on one leg without the use of arms or any other assistance. They must also count out loud until instructed to stop. The accuracy rate for this test is 65 percent, or just 15 percent better than a coin toss

Another test measures an involuntary and natural jerking motion of the eye that may be more pronounced if a person has consumed alcohol. This is the most accurate test but even still has an accuracy rate of only 77 percent.

If all three tests are used, the combined accuracy rate is 82 percent. Remembering that polygraph tests, that have accuracy results in the 90s, are determined to be inadmissible because they are not "accurate enough" for use in a criminal trial, it is easy to see how the evidentiary bar has been lowered by the lobbying efforts of special interest groups in cases involving drinking and driving.

Complicating factors

Many things might make it impossible for a driver to successfully pass one or all of these tests, even if they have not consumed alcohol. Many medical conditions might result in problems balancing such as joint, back or weight issues. A nystagmus may be impacted by a neurological problem. Road conditions, weather and even the shoes worn by a driver may also play into a person's ability to perform these tests.

With serious penalties on the line, it is important for Minnesota residents to know that the accuracy of these tests is something they should talk to an attorney about. Even for a first offense, a person might be subject to time in jail, high fines and the loss of driving privileges.