There are six categories of Driving Under the Influence (DUI) in Illinois. 625 ILCS 5/11-501 These include driving under the influence of legally prescribed drugs, driving under the influence of any compound that causes driving impairment (“huffing”), driving with any amount of an illegal substance in your system, even if you are not under the influence and driving with a combination of the above so that it causes impairment.
But by far the most common type of DUI arrest in Illinois involves alcohol. Under the alcohol category are two kinds of DUI.
One is DUI that causes bad driving, proven by the officer’s observations and your performance on standardized field sobriety tests (SFTS). The other is driving with a BAC of .08 or greater, which does not require proof of actual impaired driving due to alcohol.
There is one type of breath test device that provides what is knowns as a “Preliminary Breath Test” (PBT). It is a small, handheld device that the users blows into.
The results of the PBT cannot be used as evidence of your blood alcohol content (BAL) or to prove beyond a reasonable doubt that your BAL was .08 or higher. 625 ILCS 5/11051.5 Before the police can arrest a driver for DUI, they must establish probable cause that the driver is under the influence.
The tools available to the police for maklng this determination include standardized field sobriety tests which includes the horizontal gaze nystagimus (HGN) where the officer passes a small object in front of the subject’s eyes, the one-legged stand (stand on one leg for 30 seconds) and the walk-and-turn (take 9 steps, turn around and take 9 steps back). In addition, the PBT law states that if the officer has reasonable suspicion to believe the person is under the influence, he may request a PBT and consider the results of it in reaching a probable cause determination and in requesting further tests.