DUI Lawyer Serving Chicago

Are Field Sobriety Tests Accurate?

If you were arrested for DUI and are facing charges based upon field sobriety test results, you most likely are wondering how accurate these tests are. With a complete understanding of how these tests are administered and their inherent faults, I can provide my experienced counsel as a Chicago DUI lawyer to help you.

For field sobriety tests to yield the most accurate results possible, they must be administered in a precise manner. It is also important for three particular tests to be administered: the Horizontal Gaze Nystagmus, Walk-and-Turn and One-Leg Stand. Even when these tests are administered accurately and the results evaluated properly, however, their results will not be 100% accurate. According to NHTSA (National Highway Traffic Safety Administration) research, these tests may yield results of varying accuracies*:

Horizontal Gaze Nystagmus (HGN) – proper classification of approximately 88% of subjects.

Walk-and-Turn (WAT) – approximately 79% accuracy.

One-Leg Stand (OLS) – accurate in approximately 83% of subjects.

When all three tests are administered accurately, they may yield accurate results in 91% of cases.

Chicago DUI Attorney for Field Sobriety Tests

Although a field sobriety test may be considered to properly determine whether a driver is intoxicated or under the influence of a controlled substance, they are not completely accurate. In addition to being prone to improper administration by law enforcement, there is the possibility that factors unrelated to drugs or alcohol may contribute to a “failed” field sobriety test. A natural inability to balance, age, weight, physical injury, nervousness and even the shoes a driver is wearing may impact his or her performance. After all, these tests gauge balance, coordination and an ability to follow instructions – all things that may naturally vary from driver to driver.

Contact a Chicago DUI attorney today to talk about your testing and DUI charges.

*According to NHTSA “Appendix A Standardized Field Sobriety Testing.”