For anyone 21 or older, the mere act of consuming alcohol to the point of physical impairment is legal. There really is no such thing as being “legally intoxicated”.
What is against the law is operating a motor vehicle with enough alcohol in your bloodstream to be impaired. The offense of Driving Under the Influence (DUI) is defined in Illinois law. 625 ILCS 5/11-501.
Illinois has accepted that if you have a blood alcohol content (BAC) of .08 or higher, you are a sufficient risk to the public safety and should not be driving. It is not necessary for the state to prove that you are in fact impaired.
The mere fact of a .08 or greater BAC is illegal if proven. 625 ILCS 5/11-501(a)(1); People v. Ziltz, 98 Ill. 2d 38, 74 Ill. Dec. 40, 455 N.E.2d 70 (1983). This is known as a “per se” violation.
There is also a separate DUI law under which the state must prove actual impairment. This is the charge the state must sustain if you refuse to provide a blood or breath sample upon request, as provided for by law. 625 ILCS 5/11-501.1
The law itself simply states that you shall not drive or be in actual physical control of any vehicle within the state of Illinois while under the influence of alcohol. 625 ILCS 5/11-501(a)(2) This seemingly simple sentence raises a host of questions.
First, is it illegal to drive drunk in private property? The answer is “yes”. People v. Guynn, 33 Ill. App. 3d 736, 338 N.E.2d 239 (3 Dist. 1975); City of Highland Park v. Block, 48 Ill. App. 3d 241, 6 Ill. Dec. 285, 362 N.E.2d 1107 (2 Dist. 1977). The reason for this is that, unlike the statutory summary suspension (SSS) law, which only applies to what happens on the public highways, the language of the DUI law refers to anywhere “within the state of Illinois” and obviously includes private property.
Another aspect of a DUI involves driving or in “actual physical control” of a motor vehicle. You do not have to be “driving” the vehicle.
Many arrests occur while the driver is “sleeping it off”. Urban legend has it that to prove actual physical control, the police must find you behind the wheel with the keys in the ignition. Not necessarily.


