If you know someone who has been charged with a drunk driving offense, you might be wondering just what evidence the police officer or officers involved may have used to support making the arrest. Contrary to what you and many other people may think, the field sobriety tests commonly used before a person is arrested for driving under the influence are not able to conclusively prove that they were actually impaired.
According to FieldSobrietyTests.org, there are three standardized field tests approved for use by the National Highway Traffic Safety Administration. Their purpose is not to prove a person's guilt but to collect results that shows the potential for impairment. It is this potential impairment that is needed for a law enforcement officer to legally place a person under arrest and charge them with a DUI crime.
It is also important for you to know that these three field sobriety tests have known accuracy issues. The test that measures an involuntary eye jerk is the most reliable and even that has an accuracy rating of only 77 percent. The other two tests, the walk-and-turn test and the one-leg stand test, are said to have accuracy rates of 65 percent and 68 percent. Collectively the three field sobriety tests are said to be 82-percent accurate.
This information is not intended to provide legal advice but is instead meant to give residents in Illinois an idea of what field sobriety tests can and cannot show and how they are used during a drunk driving investigation and arrest.