Standardized Field Sobriety Tests (SFST)

There are several police coordination exercises that citizens are asked to complete when they are stopped and suspected of DWI. These so called “tests” are said to provide an indication that a person is intoxicated and are used to prove intoxication when a suspect does not give a breath or blood sample. You can view the history and propaganda about these tests from the National Highway and Transportation Safety Administration website.

They are usually recorded at the scene of the arrest. If you are suspected of DWI and the officer asks you to perform any of these, you have the right to refuse. Exercise that right. You do not have to take these “tests.” The officer is not going to release you after you complete these skills exercises. You are not proving your innocence . . . you are providing evidence for the officer to arrest you.

The exercises that have been approved by National Highway Traffic Safety Administration (NHTSA) are as follows:

Horizontal Gaze Nystagmus (HGN)

This is the “eye test” that we have all seen performed. It is supposed to correctly identify intoxication in an individual through increased eye “jerking” when the eye is made to follow a moving object to the outside and inside of their field of vision.

This test is said to have a success rate of 77% to 88% when used alone. That means that 1 in 3 or 1 in 5 people will be falsely accused of DWI when this test is used, under the best conditions and assuming it is performed exactly as required by NHTSA.

When used in combination with the other two “tests” below, the claimed success rate is 81% to 91%. Assuming that these numbers are correct and the tests are performed exactly as they should be, that means that 1 in 5 or 1 in 10 people will be falsely accused and arrested for DWI/DUI.

Many people will exhibit some Nystagmus, or jerking, as their eyes track to the extreme side. However, as people become more intoxicated, the onset of the Nystagmus, or jerking, occurs after fewer degrees of lateral deviation, and the jerking at more extreme angles becomes distinct.

If an officer decides that he has “observed” 4 or more clues, then you have “failed” the “test.”

Walk and Turn (WAT)

This test is the “walking the line” test. It is given in two parts. The first part requires the subject to balance heel-to-toe while listening to the instructions. In other words, the subject must do two things at once – balance heel-to-toe and listen to the instructions. Doing two things at once is very difficult for an intoxicated person. The second part of the test requires that the subject take nine steps, on a line, touching heel to toe and then turning around and doing it again in the opposite direction. The test is said to have a success rate of between 68% and 79% when used alone. That means that 1 in 3 to 1 in 5 people will be falsely accused of DWI/DUI. It is supposed to be increasingly reliable as it is used in combination with other tests, similar to the above.

If the officer decides he has observed two or more “clues”, then you have failed the test.

One-Leg Stand (OLS)

This test consists of the subject standing straight and raising one leg off the ground at approximately six inches, with their eyes closed and counting to 30. The time requirement is important because it makes the test sensitive to drivers with Blood Alcohol Content in the .10 percent to .15 percent range who may pass the test if they only have to balance for 10 to 20 seconds.

This tests success rate varies between 65% and 83%, when used alone. Again, this means that 1 out of 2 to 1 out of 5 people will be falsely accused, if this test is performed exactly as prescribed.

If an officer decides he has “observed” two or more “clues”, then you have failed the “test.”

Why don’t these tests work?

There are numerous problems with all of these tests.

They were supposed to have been developed in a laboratory setting and subjected to scientific principles. However, this never happened. These tests were developed and propounded as the answer to determining a driver’s impairment and have never been validly shown to have any relation to impaired driving. They have not been proven to test what their proponents claim they test. They have never been subjected to scrutiny and survived obvious flaws in their design and accuracy.

Another problem is that these tests were never subjected to scientific review by anyone other than their proponents. For a scientific principle to be valid it must be reliable and repeatable. Others that have conducted the same tests were not able to recreate the success rates claimed by NHTSA. In fact, test results from other studies have shown that an officer conducting these tests on a moderately impaired driver may as well flip a coin! One study showed that police officers should flip a coin because they were less successful in identifying impaired drivers than if they had flipped a coin and made their decision! They were less successful in determining impairment than chance.

Compound these problems with the fact that a roadside stop is never made under ideal conditions. Traffic is whizzing by, lights are flashing, your adrenaline is pumping from “black and white fever” and you are nervous and possibly upset from being stopped. None of this was taken into account when these “tests” were conducted by NHTSA and they have all be shown to have dramatic effects in the performance of these tests.

Contact us about your legal matter today!