Illinois lawDui

DUI Penalties in Illinois

September 28, 2026 · LawDiver Research Team

Illinois's rule on DUI penalties turns on a feature the national template does not capture: BAC limits: 0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21. A first offense: First-offense DUI is typically a misdemeanor Class A with fines, possible jail, supervision eligibility for some first offenders, license consequences, and evaluation/treatment. Felony threshold: A third DUI (or aggravated DUI in defined circumstances, including with a child passenger or revoked license) can be a felony. The controlling authority is 625 ILCS 5/11-501. Lookback: Prior DUI convictions within lifetime can enhance; statutory lookbacks for certain enhancements commonly use 5- or 10-year windows depending on the provision.. Ignition interlock: Ignition interlock / BAIID is required for many DUI offenders seeking restricted driving permits through the Secretary of State.

Key takeaways

BAC limits: 0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21
Lookback period: Prior DUI convictions within lifetime can enhance; statutory lookbacks for certain enhancements commonly use 5- or 10-year windows depending on the provision.
First-offense range: First-offense DUI is typically a misdemeanor Class A with fines, possible jail, supervision eligibility for some first offenders, license consequences, and evaluation/treatment.
Felony threshold: A third DUI (or aggravated DUI in defined circumstances, including with a child passenger or revoked license) can be a felony.
Ignition interlock: Ignition interlock / BAIID is required for many DUI offenders seeking restricted driving permits through the Secretary of State.
Primary authority: 625 ILCS 5/11-501.

Worked example under Illinois law

The illustration below uses only rules already stated for Illinois. It is a research hypothetical, not a prediction of what a court will do.

A driver in Illinois is charged with a first impaired-driving offense and wants to know what the statute actually sets.

Start with the alcohol limits: 0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21
Read the first-offense range: First-offense DUI is typically a misdemeanor Class A with fines, possible jail, supervision eligibility for some first offenders, license consequences, and evaluation/treatment.
Ask when the charge becomes a felony: A third DUI (or aggravated DUI in defined circumstances, including with a child passenger or revoked license) can be a felony. Lookback: Prior DUI convictions within lifetime can enhance; statutory lookbacks for certain enhancements commonly use 5- or 10-year windows depending on the provision.
Interlock: Ignition interlock / BAIID is required for many DUI offenders seeking restricted driving permits through the Secretary of State.

Illinois DUI under 625 ILCS 5/11-501 proceeds in circuit court with parallel Secretary of State summary suspension. Drivers must file a petition to rescind quickly. Defense reviews the stop and breath/blood record.

Blood alcohol limits in Illinois

0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21

Lookback window for prior offenses

Prior DUI convictions within lifetime can enhance; statutory lookbacks for certain enhancements commonly use 5- or 10-year windows depending on the provision.

First-offense penalties

First-offense DUI is typically a misdemeanor Class A with fines, possible jail, supervision eligibility for some first offenders, license consequences, and evaluation/treatment.

When a Illinois DUI becomes a felony

A third DUI (or aggravated DUI in defined circumstances, including with a child passenger or revoked license) can be a felony.

Ignition interlock and license consequences

Ignition interlock / BAIID is required for many DUI offenders seeking restricted driving permits through the Secretary of State.

How a typical Illinois DUI case unfolds

Case law: DUI penalties in Illinois

The PEOPLE OF THE STATE OF ILLINOIS, Appellee, v. LARRY LAVALLIER, Appellant

The PEOPLE OF THE STATE OF ILLINOIS, Appellee, v. LARRY LAVALLIER, Appellant, 187 Ill. 2d 464 (1999)

…rry Lavallier, was found guilty of two counts of aggravated driving under the influence of alcohol (aggravated DUI). Defendant was sentenced to a term of six years’ imprisonment on each conviction. The terms were to be served concurrently. The appellate court affirmed. 298 Ill. App. 3d 648. We granted defendant’s petition for leave to appeal. 177 Ill. 2d R. 315(a). BACKGROUND T…

The PEOPLE OF THE STATE OF ILLINOIS, Appellee, v. LARRY LAVALLIER, Appellant is worth reading on Illinois DUI penalties because the court put the point in its own words: "Lavallier, was found guilty of two counts of aggravated driving under the influence of alcohol (aggravated DUI). Defendant was sentenced to a term of six years’ imprisonment on each conviction. The terms were to be served concurrently. The appellate court affirmed. 298 Ill. App." Use that passage as the starting point, then read the facts that precede it.

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. LISA FORTNEY, Defendant-Appellant

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. LISA FORTNEY, Defendant-Appellant, 297 Ill. App. 3d 79 (1998)

…ial court erroneously determined the time of her arrest for driving under the influence; (2) the arresting officer lacked reasonable grounds to arrest her for driving under the influence; (3) her breathalyzer test results did not indicate a blood-alcohol concentration of 0.10 or more; and (4) the trial court erroneously allowed the State to introduce hearsay testimony. FACTS On…

Illinois opinions such as The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. LISA FORTNEY, Defendant-Appellant are cited where DUI penalties is disputed. The court stated: "ial court erroneously determined the time of her arrest for driving under the influence; (2) the arresting officer lacked reasonable grounds to arrest her for driving under the influence; (3) her breathalyzer test results did not indicate a blood-alcohol concentration of 0.10 or" That is the language to brief; the rest of the decision supplies the procedural posture.

The PEOPLE OF THE STATE OF ILLINOIS, Appellant, v. ERIN B. MURPHY, Appellee

The PEOPLE OF THE STATE OF ILLINOIS, Appellant, v. ERIN B. MURPHY, Appellee, 108 Ill. 2d 228 (1985)

…le only to the offense “defined in section 11 — 501,” i.e., driving under the influence. The appellate court’s holding here and in People v. Emrich (1985), 132 Ill. App. 3d 547, rested its interpretation of the section only on the introductory language “[u]pon the trial of any civil or criminal action or proceeding,” and did not give effect to the qualifying language “arising o…

On DUI penalties, The PEOPLE OF THE STATE OF ILLINOIS, Appellant, v. ERIN B. MURPHY, Appellee speaks to the Illinois dispute in this passage: "The appellate court’s holding here and in People v. Emrich (1985), 132 Ill. App." The surrounding opinion shows how the court applied that language to the record.

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. DAVID JACQUITH, Defendant-Appellant

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. DAVID JACQUITH, Defendant-Appellant, 129 Ill. App. 3d 107 (1984)

…d alcohol abuse, as well as in making over 100 arrests for “driving under the influence,” that the defendant was under the influence of both alcohol and drugs at the time of his arrest. The State’s final witness, Melissa Stahl, described defendant’s actions and stated, in contradiction to the police officers, that both officers had to assist defendant in getting out of his car.…

Practitioners open The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. DAVID JACQUITH, Defendant-Appellant when Illinois DUI penalties turns on the distinction in this sentence: "The State’s final witness, Melissa Stahl, described defendant’s actions and stated, in contradiction to the police officers, that both officers had to assist defendant in getting out of his car." Do not lift it out of the facts the court was deciding.

People v. Phillips

People v. Phillips, 2015 IL App (1st) 131147 (2015)

…PINION ¶1 Defendant Jermaine Phillips seeks reversal of his driving under the influence (DUI) conviction on the basis that the evidence failed to prove his guilt beyond a reasonable doubt in that: (i) he had a blood-alcohol concentration of 0.059; (ii) the police officer improperly administered one of the field-sobriety tests; and (iii) the other circumstantial evidence of his…

People v. Phillips is worth reading on Illinois DUI penalties because the court put the point in its own words: "PINION ¶1 Defendant Jermaine Phillips seeks reversal of his driving under the influence (DUI) conviction on the basis that the evidence failed to prove his guilt beyond a reasonable doubt in that: (i) he had a blood-alcohol concentration of 0." Use that passage as the starting point, then read the facts that precede it.

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. DAVID UTT, Defendant-Appellant

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. DAVID UTT, Defendant-Appellant, 122 Ill. App. 3d 272 (1983)

…rent prison terms of 364 days, two years and six months for driving under the influence, possession of a controlled substance and resisting a police officer, respectively; and ordered to pay a fíne and court costs totalling $50 for improper lane usage. (Cause No. 82 — 691.) In addition, the defendant’s court supervision, which had been imposed for a March 3, 1982, driving under…

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. DAVID UTT, Defendant-Appellant is worth reading on Illinois DUI penalties because the court put the point in its own words: "rent prison terms of 364 days, two years and six months for driving under the influence, possession of a controlled substance and resisting a police officer, respectively; and ordered to pay a fíne and court costs totalling $50 for improper lane usage. (Cause No. 82 — 691.) In ad" Use that passage as the starting point, then read the facts that precede it.

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. CHARLES ATWELL, Defendant-Appellant

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. CHARLES ATWELL, Defendant-Appellant, 129 Ill. App. 3d 724 (1984)

…complaint was defective because it did not charge him with driving under the influence of alcohol or driving under the influence of any other drug. In People v. Featherstone (1974), 23 Ill. App. 3d 492, 318 N.E.2d 756, we reversed a conviction where the defendant had been charged with a violation of section 11— 501 of the Illinois Vehicle Code (Ill. Rev. Stat. 1971, ch. 951/2,…

Illinois opinions such as The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. CHARLES ATWELL, Defendant-Appellant are cited where DUI penalties is disputed. The court stated: "In People v. Featherstone (1974), 23 Ill. App. 3d 492, 318 N.E.2d 756, we reversed a conviction where the defendant had been charged with a violation of section 11— 501 of the Illinois Vehicle Code (Ill. Rev. Stat. 1971, ch." That is the language to brief; the rest of the decision supplies the procedural posture.

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. PATRICK FOLEY, Defendant-Appellant

The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. PATRICK FOLEY, Defendant-Appellant, 152 Ill. App. 3d 354 (1987)

…v. Stat. 1985, ch. 95½, par. 11 — 501(a)(1)), but guilty of driving under the influence of alcohol (Ill. Rev. Stat. 1985, ch. 95½, par. 11 — 501(a)(2)). Defendant claims the verdicts are inconsistent and were the result of confusion on the part of the jury. Defendant was arrested April 8, 1984, by a Downers Grove police officer. He was taken to the police station where he volun…

Practitioners open The PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v. PATRICK FOLEY, Defendant-Appellant when Illinois DUI penalties turns on the distinction in this sentence: "Stat. 1985, ch. 95½, par. 11 — 501(a)(1)), but guilty of driving under the influence of alcohol (Ill. Rev. Stat. 1985, ch. 95½, par. 11 — 501(a)(2)). Defendant claims the verdicts are inconsistent and were the result of confusion on the part of the jury." Do not lift it out of the facts the court was deciding.

Frequently asked questions

What is the legal BAC limit in Illinois?