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What tools are available to the police in Illinois for proving a DUI charge?

At one time, an arrest for Driving Under the Influence (DUI) was not that big of a deal. Many such charges were reduced to reckless driving so that the driver did not lose his or her driver’s license.

Even when a DUI conviction did occur, there was normally a small fine and after a short period of time, the driver was allowed to drive again. In addition, breath tests were optional and there was no downside in not agreeing to take a test.

The legal blood alcohol level (BAL) was high. Finally, even if a breath test existed, the state was still required to prove you were intoxicated at the time you were driving the car.

Today, the consequences of a DUI arrest, much less a conviction, are more serious. The police have developed more sophisticated investigative tools, such as the Horizontal Gaze Nystagumus (HGN), the walk-and-turn and the one-legged stand.

These are tests that, law enforcement alleges, are designed to determine whether your ability to perform physical tasks required to drive are impaired by alcohol. Results of your performance on these tests are often recorded on video cameras affixed to police cruiser dashboards.

These recordings are admissible in court. Furthermore, Illinois law allows police to ask you to provide a breath sample into a Preliminary Breath Test (PBT) in order to help in establishing whether there is probable cause to believe you may be under the influence of alcohol.

While PBT results are admissible to help the state establish that the police officer had a basis to believe you might be under the influence, the results themselves cannot be used to establish actual guilt. People v. Rose, 268 Ill. App. 3d 174, 205 Ill. Dec. 574, 643 N.E.2d 865 (4 Dist. 1994) Moreover, the accused is entitled to refuse to take the PBT and there is no penalty for doing so. 625 ILCS 5/11-501.5


On the other hand, if the law enforcement officer believes you are intoxicated, you will be arrested for DUI and then asked to take a “chemical test”. This test consists of either a blood draw or a breath test that purportedly provides an accurate reading of your BAL. As a consequence, the results of these tests are admissible in court to prove your BAL level. 625 ILCS 5/11-501.2
In addition, Illinois now has a “per se” law , a Latin phrase that in the context of DUI law means that if your BAL Is above a certain level, that in and of itself, without any added proof of intoxication, is enough evidence to sustain a DUI charge. In Illinois, the BAL is .08.

If there is no BAL or the BAL is under .08, you can still be charged with DUI. To sustain this type of charge, the state must show that your ability to act with reasonable care was impaired due to alcohol. Evidence such as your performance on the standardized field sobriety tests (SFST), which includes the HGN, walk-and-turn and one-legged stand constitutes a piece of the puzzle. Your driving performance is another.

The jury may also hear about difficulty finding your driver’s license, registration and insurance card. Other common indicators of alcohol impairment may include an odor of alcohol, slurred speech, bloodshot eyes, thick tongued, confusion about your location, time of day and destination, inability to follow instructions, staggering, swaying and poor balance etc.

Through cross examination, a defense lawyer can either explain the observations, cast doubt upon the officer’s perception of what he saw or minimize the importance of his testimony. He may obtain expert witnesses to explain your conduct and you may take the stand and explain yourself.