DUI in Illinois

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Being convicted of a DUI in Illinois can be serious and lead to significant penalties. These include jail time, fines and revocation of the defendantís driverís license.

Presumed Intoxication

Illinois presumes that anyone with a blood alcohol content level of 0.08 or higher to be intoxicated. The prosecution does not have to prove that the driver was actually impaired when his or her BAC level meets this point.

Under the Influence

Even if the individual did not have a BAC over the legal limit, he or she can still be found guilty of Driving Under the Influence. According to the Illinois jury instruction, a person is considered to be under the influence of alcohol when his or her mental or physical faculties are impaired to a degree that his or her ability to think and act with ordinary care is reduced due to drinking. For a successful conviction, the prosecution must establish that the defendant was physically or mentally less able to exercise clear judgment and operate a vehicle with steady hands and nerves.

Establishing Intoxication

In order to establish intoxication, the prosecution must present more than evidence that the individual smelled like alcohol, since this only proves that he or she consumed alcohol, not that he or she was impaired by such consumption.

One way that the prosecution may attempt to prove intoxication is by presenting evidence based on the results of a blood or breath test. Illinois law has certain presumptions based on BAC. There is a presumption that if the defendantís BAC was 0.05 or less, he or she was not under the influence of alcohol. If his or her BAC was 0.08 or more, the presumption is that he or she was under the influence of alcohol. If the BAC was somewhere between these two points, there is not a presumption that the defendant was or was not under the influence of alcohol. However, the BAC level can be taken into consideration along with other evidence.

The prosecution can rely on different evidence to prove their case. If credible testimony can be extracted from the arresting officer, the prosecution does not have to supply scientific proof of intoxication. Factors help determine his or her credibility and reliability, including the number of times he or she has arrested people charged with drunk driving and his or her experience as a law enforcement officer. Field sobriety tests may also be used as evidence of the defendantís physical or mental impairment, or even as the defendantís awareness of his or her own guilt. If a defendant refuses to take a test that could possibly be incriminating, the jury can interpret this refusal as evidence of knowledge of guilt. Other signs of guilt may include fleeing from police or mentioning that the defendant has relatives in the police force.


After the prosecution puts on evidence that supports the defendantís guilt, the defense attorney can present evidence to refute the prosecutionís evidence. One defense may be to show that the defendantís poor performance in field sobriety tests or presumed impaired driving was due to an injury or other physical condition. For example, a defendantís disability may help show that he or she was not impaired as believed by the police officer who stopped him or her. Foot injuries can help explain poor performance on a field sobriety test. A defendant who has suffered a head injury may be able to explain this condition could have affected his or her walking that the police officer interpreted as staggering because of alcohol consumption.

Another defense is to show that the prosecution has not met each element of the crime. For example, for a conviction for a DUI, the prosecution must show that the defendant was intoxicated at the time he or she was driving. There must be a connection between the defendantís condition after driving with that which he or she had while driving. A valid defense may be that the defendant was under the influence, but this impairment was after he or she was driving or before. The prosecution has the burden of showing that he or she was actually under the influence at the time he or she drove a motor vehicle. A criminal defense attorney may be able to suggest other possible defenses based on the particular circumstances of the case.

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Disclaimer: While every effort has been made to ensure the accuracy of this publication, it is not intended to provide legal advice as individual situations will differ and should be discussed with an expert and/or lawyer.

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