When an Illinois police officer suspects you of DUI, you may be asked to take one or more field sobriety tests. By law you do not have to agree to such tests. Moreover, if you take a test and “fail,” based on the officer's judgment, it may be used against you as evidence in court.

Court Rejects Peoria Officer's Arrest Based on HGN Test

However, not all field sobriety tests are afforded the same weight by judges. Nor does failure necessarily prove that you were intoxicated above the legal limit in Illinois. Therefore, it is important to challenge any test result that may be inaccurate or improperly administered by the police.

Normally an Illinois police officer must have probable cause to stop you on suspicion of a DUI. The Fourth Amendment to the U.S. Constitution protects all individuals against “unreasonable” seizures by the police. However, what if an officer stops to speak with you for another reason and subsequently discovers evidence that suggests drunk driving?

Court Reinstated Driver's License Suspension

The Fourth Amendment does not apply to “consensual encounters” with the police. In other words, if you speak to the police voluntarily, and not under coercion or detention, you cannot later invoke the Fourth Amendment to claim any evidence obtained against you was an illegal search. Of course, it may not be obvious to you at the time that an encounter was “consensual.” Consider the following case in point.