On April 21, 2011, the Illinois Supreme Court, in a unanimous 7-0 opinion, issued a ruling important to Illinois DUI lawyers. Understanding the decision requires some knowledge of Illinois DUI law.
The state has several methods at its disposal to sustain a DUI charge. The traditional means is to prove that as a result of your consumption of alcohol, your ability to drive was impaired. This is the “actual impairment” DUI.
Prosecutors were finding it too hard to prove actual impairment. Therefore, in order to stack the deck against those charged with DUI, the Illinois General Assembly passed DUI laws that make it illegal to drive with a blood alcohol level above the legal limit, which was originally .10 but is now .08.
This number represents the percent of alcohol in your bloodstream. Prosecutions that rely upon the .08 are known as “pro se alcohol” violations.
The per se blood alcohol legal limit can be measured by actual blood samples, which is expensive and time-consuming. So, to make it easier for the state to convict you of DUI, the law allows the police to demand that you give a breath sample by blowing into a mouthpiece connected to a machine (the Breathalyzer). This machine supposedly converts the breath sample into blood alcohol level equivalents.
Sometimes the police claim that a person is under the influence of illegal drugs. This is also illegal but hard to prove as it requires proof of actual impairment from the drugs.
Likewise, you may be taking legally dispensed prescription medications. The police may suspect your medications are impairing your driving. If so, you are guilty of DUI. But again, actual impairment is hard to prove.