DUI Process Guide Updated March 2026 · 18 min read · Illinois Law

The Illinois DUI
Legal Process: Step by Step

You were arrested for DUI. Now you are wondering what comes next. This page walks you through every step from the moment of arrest through final resolution, so you know exactly what to expect and where your attorney can fight for you.

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Michael F. McMahon
Former DuPage County Prosecutor · Criminal Defense Attorney · 40+ Years
46 Days
Until Suspension Starts
90 Days
Petition Deadline
2 Tracks
Criminal + Administrative
3–12 Mo.
Typical Case Duration

A DUI arrest in Illinois sets two separate legal processes in motion at the same time. Most people do not realize this until it is too late to respond to both.

The first is the criminal case: the charge filed in circuit court, handled by the State's Attorney's office. The second is the Statutory Summary Suspension: an automatic administrative action against your driving privileges that runs entirely separately from the criminal charge. Both have hard deadlines. Missing either one is costly.

Understanding the full process helps you prepare. It also helps you see where your attorney can fight for you at each stage.


Step 1: The Traffic Stop and Arrest

Your DUI case starts the moment an officer activates their lights. The officer needs reasonable suspicion of a traffic violation or impaired driving to pull you over. During the stop, the officer will look for signs of impairment: slurred speech, bloodshot eyes, odor of alcohol, or fumbling with documents.

The officer may ask you to perform field sobriety tests (FSTs) and submit to a preliminary breath test (PBT) on the roadside. These are the walk-and-turn, one-leg stand, and horizontal gaze nystagmus tests.

PBT vs. Station Test

The roadside preliminary breath test (PBT) is not admissible in court. It is used only to help the officer establish probable cause for the arrest. The evidentiary breath test at the police station is the one that counts. This distinction matters for your defense.

If the officer determines there is probable cause, they will place you under arrest and transport you to the station for a formal breath or blood test. Everything the officer observes during the stop, and every test they administer, becomes potential evidence. It also becomes potential grounds for a defense challenge.

Learn more: DUI Defense Strategies in Illinois


Step 2: Booking and Release

At the station, you will be:

  • Formally charged with DUI
  • Given a breath or blood test (or you will refuse, which triggers its own consequences)
  • Photographed and fingerprinted
  • Given paperwork including your notice of Statutory Summary Suspension
  • Given a court date for your arraignment

Most DUI defendants are released on bond the same day or the next morning. You will leave with a stack of paperwork that defines your deadlines. The most important document is the notice of Statutory Summary Suspension. This starts the 90-day clock for your petition deadline and the 46-day countdown to when your suspension begins.

Do not lose this paperwork. Your attorney will need every piece of it.


Step 3: The Statutory Summary Suspension (Automatic)

This is the administrative track. It happens automatically after your arrest, completely separate from the criminal case. It does not matter how your criminal case resolves. The suspension can still take your license if you do not act within 90 days.

SituationSuspension Length
Failed breath/blood test (first offense)6 months
Refused testing (first offense)12 months
Failed test (prior DUI or suspension)12 months
Refused testing (prior DUI or suspension)36 months
Critical Deadlines

The suspension starts 46 days after your arrest. You have 90 days from the date of your notice to file a Petition to Rescind the suspension. This is an absolute deadline. Miss it and you lose all right to challenge the suspension, regardless of how strong your case is. Your first criminal court date is almost always scheduled after this deadline has passed.

Challenging the Suspension

At the Petition to Rescind hearing, your attorney can argue that:

  • The officer did not have reasonable suspicion for the traffic stop
  • The officer did not have probable cause for the DUI arrest
  • You were not properly informed of the consequences of refusal
  • The testing equipment was not functioning properly or was not properly calibrated
  • The officer did not follow required testing procedures (including the 20-minute observation period)

A successful suspension hearing keeps you driving. It also produces discovery that often informs the defense of the underlying criminal case.

Driving During the Suspension

First-time offenders may be eligible for a Monitoring Device Driving Permit (MDDP), which allows you to drive with a BAIID (Breath Alcohol Ignition Interlock Device) installed in your vehicle. The MDDP is available once the suspension begins, but requires advance planning and installation.

Full details: DUI and Your Driver's License: Suspensions, Revocations, and Permits


Step 4: Arraignment (First Court Date)

Your arraignment is your first appearance before a judge. This is the start of the criminal track. At this hearing:

  • The charges against you are formally read
  • You enter a plea (almost always "not guilty" at this stage)
  • Bond conditions are set or reviewed
  • Your attorney can begin requesting discovery (police reports, test results, video footage)

You should have an attorney by this date. If you cannot afford one, the court will appoint a public defender. However, public defenders carry very high caseloads and typically cannot dedicate the time a serious DUI defense requires.

Hire Before Arraignment

Your first court date is often 4 to 6 weeks after arrest. But the 90-day suspension petition deadline and the need to preserve video evidence (which departments delete after 30 to 90 days) mean you should hire an attorney within days of your arrest, not weeks.


Step 5: Discovery and Pretrial Motions

This is where your attorney does the heavy lifting. Discovery is the process of collecting and reviewing all the evidence in your case. Your lawyer will request and analyze:

  • The police report and arrest narrative
  • Dashcam and bodycam footage (frame by frame if necessary)
  • Breath test machine calibration and maintenance records
  • Blood test lab results and chain of custody documentation
  • Dispatch logs and 911 call recordings
  • Officer training records and certification status
  • Witness statements

Pretrial Motions

Based on what they find, your attorney may file motions that can reshape or end your case:

  • Motion to Suppress Evidence. If the traffic stop was illegal, or the breath test was improperly administered, or the arrest lacked probable cause, the evidence may be thrown out. This is the motion that produces dismissals.
  • Motion to Dismiss. If there is a fundamental legal problem with the charges or the prosecution's case.
  • Petition to Rescind Suspension. The formal challenge to the automatic license suspension (discussed in Step 3).
  • Motion for Additional Discovery. If the prosecution has not turned over all evidence as required.

The outcome of these motions often determines the entire case. A successful motion to suppress can eliminate the prosecution's key evidence, leaving them with nothing to proceed on.

Learn more: DUI Defense Strategies in Illinois


Step 6: Plea Negotiation

Most DUI cases are resolved through negotiation, not trial. Your attorney and the prosecutor will discuss possible outcomes, which may include:

  • Court supervision (first offense only). Avoids a conviction on your record if you complete all conditions.
  • Reduced charges. For example, reckless driving instead of DUI. This avoids DUI-specific license consequences and the permanent expungement bar.
  • Agreed sentencing terms. Specific fines, classes, community service hours, and probation length negotiated in advance.
  • Dismissal. If pretrial motions have weakened the prosecution's case significantly.

A good DUI attorney knows what deals are realistic based on the evidence, the court, and the specific prosecutor assigned to your case. In DuPage County, these negotiations are directly influenced by your attorney's relationship with the State's Attorney's office and their reputation in the courthouse.

Your attorney will advise you on whether to accept an offer or push for trial. This decision should never be rushed.


Step 7: Trial

If your case goes to trial, you can choose a bench trial (judge decides) or a jury trial (12 jurors decide). The prosecution must prove beyond a reasonable doubt that you were:

  • Operating a motor vehicle
  • On a public road in Illinois
  • While under the influence of alcohol, drugs, or intoxicating compounds (or with a BAC of 0.08 or higher)

Your attorney will cross-examine the arresting officer, challenge the testing evidence, present your defense, and argue to the judge or jury why the prosecution has not met its burden.

The choice between a bench trial and jury trial is strategic. In DuPage County, Judge Pierce's knowledge of every judge on the 18th Circuit bench directly informs which format gives you the best chance in your specific case.

If the prosecution cannot prove every element beyond a reasonable doubt, you are found not guilty.


Step 8: Sentencing (If Convicted)

If you plead guilty or are found guilty, the judge will impose a sentence based on the offense level and any aggravating or mitigating factors. Your attorney's job at sentencing is to present every mitigating factor available: your employment, family ties, community involvement, any treatment you have already started, and character references.

Sentencing can include jail time, fines, probation, community service, DUI evaluation and treatment, and license revocation. The specific penalties depend on your offense number and circumstances.

See all possible penalties: Illinois DUI Penalties: Complete Sentencing Guide


Step 9: Post-Conviction Options

Even after a conviction, you may have options:

  • Appeal the conviction if there were legal errors during the trial or in pretrial rulings
  • Apply for a Restricted Driving Permit (RDP) to drive for work, school, or medical appointments during a revocation
  • Petition for early termination of probation if you have complied with all conditions
  • Explore expungement if you received court supervision (not a conviction) and completed all requirements
  • Request a formal hearing with the Secretary of State for license reinstatement after the revocation period

More on clearing your record: DUI Expungement in Illinois

More on license reinstatement: DUI and Your Driver's License


Typical DUI Case Timeline in DuPage County

StageTypical TimeframeKey Action
Arrest to arraignment2 to 6 weeksHire attorney, file suspension petition, preserve video evidence
Day 4646 days after arrestSuspension begins (unless successfully challenged)
Day 9090 days after arrestAbsolute deadline to file Petition to Rescind suspension
Discovery and motions2 to 4 monthsCollect evidence, file suppression motions, challenge testing
Plea negotiationOngoing during discoveryNegotiate supervision, reduction, or dismissal
Trial (if needed)4 to 8 months after arrestBench or jury trial
Total case resolution3 to 12 monthsVaries by complexity and whether case goes to trial

Every case is different. Complex cases or cases with contested motions can take longer. Cases where a strong suppression motion leads to dismissal can resolve more quickly.


Understanding the Two Tracks: Criminal vs. Administrative

One of the most confusing aspects of an Illinois DUI is that two separate legal proceedings run simultaneously. Here is how they compare:

FactorCriminal CaseAdministrative Suspension
What it isCriminal charge filed by the State's AttorneyAutomatic action against your driving privileges
Where it's heardCircuit court (Wheaton for DuPage County)Same court, but separate hearing
What triggers itThe officer's arrest and the State's Attorney's charging decisionFailing or refusing the chemical test
Key deadlineArraignment (first court date, usually 2-6 weeks)90 days from arrest to file Petition to Rescind
Possible outcomesDismissal, supervision, conviction, acquittalSuspension upheld or rescinded
Are they connected?They run independently. You can win one and lose the other. Winning the suspension hearing does not dismiss the criminal case, and a criminal dismissal does not automatically lift the suspension.

This is why acting quickly after arrest matters so much. The administrative track has a shorter deadline than the criminal track, and most people do not realize it exists until the deadline has passed.

Two Deadlines Are Running
The suspension petition deadline
won't wait for your court date.
We file the petition the day you retain us. Call for a free case review. Nights and weekends included.
Call 630-953-4400
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Written by
Michael F. McMahon

Mike McMahon is a criminal defense attorney with 40+ years of practice in DuPage County. He previously served as a prosecutor in the DuPage County State's Attorney's Office before transitioning to criminal defense. He has guided hundreds of clients through every stage of the DUI legal process in the 18th Judicial Circuit in Wheaton.

Former DuPage Prosecutor 18th Circuit 40+ Years DUI Defense Illinois Bar
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