Field Sobriety Tests

About the NHTSA Sobriety Tests

In the decades between the invention of the automobile and the early 1980s, it was largely up to the individual judgment of a law enforcement officer to determine whether an individual was driving under the influence of alcohol. If the officer wanted to ascertain whether the driver's ability to safely operate the vehicle was impaired by alcohol intoxication, he or she had to find a way to decide the issue, and this decision was often made arbitrarily. Many people were wrongfully arrested for DUI, while many drunk drivers were not detected and were sent on their way. In an effort to improve the reliability of roadside sobriety detection the National Highway Traffic Safety Administration (NHTSA) commissioned the development in the late 1970s of a standardized battery of tests. After several years, three tests were chosen as being the most reliable in determining whether a driver was ability impaired by alcohol.

Standardized Roadside Tests

One-Leg Stand
The suspect is directed to stand with one foot raised six inches off the ground while counting out loud for thirty seconds. The test may be failed if the suspect is observed to be swaying, hopping to stay on one foot, using the arms to balance or putting the raised foot on the ground.

The suspect is directed to walk in a straight line for nine steps, walking heel-to-toe, followed by pivoting on one foot and repeating the action in the opposite direction. There are many possible ways to fail the test, such as by stepping out of line, failing to step heel-to-toe, taking one too many steps, swaying with the arms or starting to walk before the officer has given the order to do so.

Horizontal Gaze Nystagmus
The officer waves a small object such as a pencil or a flashlight back and forth directly in front of the suspect's eyes. Nystagmus, an involuntary jerking of the eyes, will naturally occur at extreme angles, but if it happens before that point the suspect may be assumed to be intoxicated. Another indicator is if the suspect's eyes have difficulty in smoothly tracking the object's motion.

Are field sobriety tests accurate?

While these tests may provide a general rule of thumb for determining whether a suspect is too drunk to drive, they are not 100 percent accurate or reliable. In fact, even the NHTSA's own validation studies have demonstrated that these tests have wide margins of error. In the original study conducted in 1981, the combined battery was found to be 81 percent accurate at determining alcohol impairment, with individual tests being even less reliable. A follow-up study conducted in 1998 resulted in a finding of 91 percent reliability for the test battery. That means that there is a 9 percent likelihood that the suspect who was arrested, charged and perhaps even convicted of DUI was innocent.

Challenging Field Sobriety Tests

The fact that there is nearly a one-in-ten chance that the test was wrong raises problems in the context of criminal prosecution, since you cannot legally be convicted until you have been proven guilty beyond a reasonable doubt. Further, the 9 percent margin of error assumes that the officer did everything by the book. Factually, many DUI arrests involve field sobriety tests in which the officer made errors in explaining or administering the regimen, while in other cases the dashboard video camera footage will reveal that conditions such as gravel on the road surface, bad weather conditions or even inappropriate footwear made it difficult for the suspect to pass the test.

There is also the factor of the subjectivity of the test; to a large degree, success depends on whether or not the officer wants you to fail. With careful investigation of the evidence and aggressive cross examination of the police officer, a skilled Colorado Springs criminal defense lawyer is often able to reveal that the field sobriety tests upon which the arrest was based simply are not reliable. To learn more about this aspect of DUI defense and to begin working on a strategy for your case, contact me now at the Samuelson Law Firm for an initial consultation.