What Happens If You’re Caught Driving Under the Influence of Cannabis in Illinois?

Chicago, like the rest of Illinois, has seen major changes in the law since marijuana was legalized for recreational use in 2020. But legalization does not mean you can drive under the influence of cannabis. Illinois law enforcement continues to take DUI charges seriously, and driving after consuming marijuana—regardless of whether it was purchased legally—can lead to arrest, license suspension, and a criminal conviction. In Chicago, police officers with the Chicago Police Department, as well as state troopers and suburban departments, are trained to identify marijuana impairment through roadside evaluations and chemical testing.

Driving under the influence of cannabis in Illinois is classified as a crime under 625 ILCS 5/11-501. A first offense is typically a Class A misdemeanor, punishable by up to one year in jail and fines of up to $2,500. If aggravating circumstances are present, such as prior DUI convictions, an accident involving serious injury, or having a child passenger, the offense may be charged as a felony. The degree of the felony can range from a Class 4 to a Class 2 depending on the facts. Even a misdemeanor marijuana DUI carries long-term consequences, including license suspension, a permanent criminal record, and obstacles in employment, housing, and education.

Illinois Law on Driving Under the Influence of Cannabis

Under 625 ILCS 5/11-501(a)(7), a person is guilty of DUI if they operate a motor vehicle with a THC concentration of 5 nanograms or more per milliliter of whole blood, or 10 nanograms or more per milliliter of other bodily substances, within two hours of driving. Illinois uses both a “per se” limit and an impairment standard, meaning a person can be charged with DUI based on test results or based on observed impairment.

The cannabis DUI statute applies whether the marijuana was consumed via smoking, vaping, or edibles. Unlike alcohol, which metabolizes in predictable ways, THC can linger in the bloodstream long after impairment wears off, making testing and prosecution more complex. That complexity has become a common battleground for criminal defense attorneys in DUI cannabis cases.

A first-time cannabis DUI is usually a Class A misdemeanor unless enhanced by aggravating factors. A second offense can carry mandatory minimum jail time and longer license revocation periods. A third offense is typically charged as a Class 2 felony under 625 ILCS 5/11-501(d), which may carry a prison sentence of 3 to 7 years. Felony charges are also possible in cases involving bodily harm, minor passengers, or driving without a valid license.

What Happens When You’re Investigated for DUI of Cannabis in Illinois

A marijuana DUI case often begins with a traffic stop. Officers might observe erratic driving, lane weaving, or delayed reactions. Once stopped, they may look for signs of impairment such as red eyes, the smell of cannabis, slow speech, or confusion. If they suspect drug use, they may request a roadside field sobriety test. Illinois does not currently have a roadside test that accurately measures cannabis intoxication, so officers rely on traditional methods such as the walk-and-turn, one-leg stand, and horizontal gaze nystagmus (HGN)—although the HGN is not validated for drug detection.

If officers believe there is probable cause, they may arrest the driver and request chemical testing—usually through a blood or urine sample. Refusing testing results in automatic statutory summary suspension of driving privileges under 625 ILCS 5/11-501.1. Chemical testing is often delayed, which can impact THC levels and affect prosecutorial strategy.

The investigation stage also includes police reports, witness statements, and body camera footage. All of these can be challenged in a DUI defense if proper procedures were not followed or if constitutional rights were violated.

The Penalties and Punishments for a Cannabis DUI Conviction in Illinois

A conviction for a marijuana-related DUI has wide-reaching consequences in Illinois. A first offense Class A misdemeanor under 625 ILCS 5/11-501(d)(1)(H) carries up to one year in jail, a $2,500 fine, and a minimum one-year revocation of driving privileges. Even if jail time is not imposed, the driver will face court supervision, mandatory drug education classes, and a permanent mark on their criminal record.

A second conviction within five years results in a mandatory five-day jail sentence or 240 hours of community service, a longer license revocation, and higher fines. A third conviction is classified as a Class 2 felony and can include prison time up to 7 years. If a person is convicted while transporting a minor, under 625 ILCS 5/11-501(c)(3), the penalties are enhanced significantly.

In addition to criminal penalties, those convicted will have difficulty maintaining a valid driver’s license. A statutory summary suspension takes effect 46 days after a failed test or refusal. Reinstatement requires participation in a hearing through the Illinois Secretary of State’s Office and may require the use of a Breath Alcohol Ignition Interlock Device (BAIID), even for marijuana DUIs.

The Criminal Trial Defense Process in a Marijuana DUI Case

Once charged, the case enters the court system. The initial court appearance is called the arraignment, where the charges are formally presented. After that, the case proceeds to pre-trial hearings where your attorney may file motions to suppress evidence, challenge the arresting officer’s observations, or argue against the admissibility of chemical test results.

Pre-trial discovery allows both the defense and prosecution to examine the evidence. Your attorney may request lab reports, squad car and bodycam video, field sobriety test performance, and records related to the chemical testing device used.

An experienced defense lawyer can also challenge the prosecution’s interpretation of the test results. For example, a defense may argue that the presence of THC in the bloodstream did not equate to impairment at the time of driving. This distinction is important, as Illinois does not criminalize driving with THC in your system unless impairment can be shown or the legal thresholds are exceeded.

A trial may follow if a plea agreement is not reached. During the trial, the defense may cross-examine the arresting officer, present expert witnesses in toxicology, and contest the chain of custody and reliability of the blood test. Illinois DUI cases are tried before a judge or jury, and a conviction requires proof beyond a reasonable doubt.

Example Case: Defending Against a Cannabis DUI in Cook County

In a recent case we handled in Cook County, a 29-year-old driver was charged with DUI after being pulled over for a broken taillight. The officer claimed to smell marijuana and observed bloodshot eyes. Our client admitted to using cannabis the night before but denied being impaired. Field sobriety tests were inconclusive, but he was taken in for a blood draw. Results showed 7 nanograms of THC per milliliter of blood—over the legal limit.

We challenged the timeline and argued the THC presence was residual from lawful use the previous evening. Our toxicology expert testified about the disconnect between THC concentration and actual impairment. We also cross-examined the officer regarding the reliability of roadside observations. After a full trial, the judge found reasonable doubt and dismissed the charges.

What Police Try to Use Against You in Cannabis DUI Cases

Law enforcement builds cannabis DUI cases on a combination of subjective and scientific evidence. Officers rely heavily on their observations of the driver’s behavior, appearance, and responses to field sobriety tests. They may also cite the presence of marijuana in the vehicle, admission of use, or the smell of burnt cannabis.

Chemical tests are increasingly relied upon but come with challenges. THC blood levels do not align neatly with impairment like blood alcohol content does. The timing of the test, whether the sample was properly stored, and the qualifications of the lab technician all come into play. The prosecution may also present Drug Recognition Experts (DREs) to testify, though their credentials and methodologies can be cross-examined.

Why You Need an Attorney for Every Step of the Criminal Case Process

From the moment of arrest to the final court hearing, the criminal case process in Illinois is filled with opportunities for error, overreach, and misinterpretation. An attorney can represent you at the bond hearing, obtain discovery materials, challenge the legality of the traffic stop, and argue against the admissibility of your test results.

Without an attorney, you risk accepting plea deals that are not in your interest, losing your license without a fight, and suffering a criminal conviction that could have been avoided. Every stage—arrest, arraignment, pre-trial motions, and trial—requires strategy, legal knowledge, and negotiation skill.

Legal Defenses to a Cannabis DUI in Illinois

There are several defenses available in marijuana DUI cases. The most common include challenging the stop as lacking reasonable suspicion, suppressing evidence obtained without probable cause, arguing the THC levels do not reflect impairment, and attacking the validity of field sobriety tests or chemical results.

In cases where the test was delayed or improperly handled, the defense may argue that the results are unreliable or inadmissible. A well-supported expert witness can help convince the court or jury that THC alone does not equate to impaired driving.

What to Look for in a Criminal Defense Attorney in Illinois

You should seek an attorney who focuses exclusively on criminal defense and who has extensive courtroom experience in Illinois, particularly Cook County. Look for someone who has tried marijuana DUI cases, understands forensic toxicology, and can assess the weaknesses in the state’s evidence.

Effective communication is key. Your attorney should explain the charges, possible outcomes, and legal strategies clearly and honestly. Trial skill, local reputation, and access to qualified experts all matter when the stakes include jail time and license loss.

What to Ask During Your Free Consultation

When you sit down for your consultation, ask the attorney how many DUI cannabis cases they have handled, what percentage go to trial, what strategies have been most successful, and whether they are familiar with the prosecutors and judges in your jurisdiction. Ask about timelines, expected outcomes, and what to expect at each phase of the case.

Also inquire about the attorney’s availability, how often they’ll communicate with you, and whether they will personally handle your case or delegate to another attorney.

Chicago Criminal Defense FAQs – Cannabis DUI in Illinois

Can I be charged with DUI in Illinois even if I used cannabis legally?
Yes. Legal use of cannabis does not mean you can drive while impaired. If police suspect you are under the influence and your THC level exceeds the statutory limit or you show signs of impairment, you can be charged. It doesn’t matter if the marijuana was obtained legally from a dispensary or with a medical card.

What are the penalties for a first-time cannabis DUI in Illinois?
A first-time offense is a Class A misdemeanor, punishable by up to one year in jail and a fine up to $2,500. Your driver’s license will be revoked for a minimum of one year. You may also be required to complete a drug education course and install a BAIID if driving privileges are restored early.

Is there a roadside test for marijuana like a breathalyzer for alcohol?
No. Illinois law enforcement currently uses standard field sobriety tests and officer observations. While chemical tests (blood or urine) can confirm THC in your system, there is no reliable roadside device for cannabis impairment detection. This gap often creates challenges in court for prosecutors.

What happens if I refuse chemical testing?
Refusing a blood or urine test will result in an automatic statutory summary suspension of your driver’s license. The length of suspension can be longer than if you had taken the test and failed. The refusal can also be used as evidence of guilt at trial.

Can THC stay in my system even if I’m not high?
Yes. THC can be detected in your blood or urine for days or even weeks after use, depending on frequency. This is one of the main issues in DUI cannabis cases: testing positive for THC does not necessarily mean you were impaired while driving.

Can I be charged with DUI even if my blood THC level is under the legal limit?
Yes. Illinois law allows for DUI charges based on observable impairment, regardless of THC level. If an officer believes you are impaired and you show poor coordination, confusion, or fail field sobriety tests, you may still be arrested even if your test results are below 5 nanograms.

Will I lose my job if I’m convicted of a marijuana DUI?
It’s possible. Many employers conduct background checks, and a DUI conviction is a red flag—especially if your job involves driving, government contracts, or working with vulnerable populations. A conviction can also disqualify you from professional licensing in some fields.

Do I need an attorney even if it’s my first offense?
Yes. Even a first offense can have permanent consequences. An attorney may be able to negotiate a reduction or dismissal, file motions to suppress evidence, or take the case to trial. Going without a lawyer leaves you vulnerable to maximum penalties and a lifelong criminal record.

Can my marijuana DUI be expunged from my record?
Generally, DUI convictions in Illinois cannot be expunged or sealed. This makes it critical to fight the charges from the beginning. However, if the charges are dropped or you are found not guilty, you may be able to have your arrest record cleared.

What if I was using medical marijuana?
Even with a valid medical marijuana card, you are not permitted to drive while impaired. A medical marijuana user may still be charged with DUI if officers believe their ability to drive was affected. The card does not offer immunity from criminal prosecution.

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Why You Need a Criminal Defense Lawyer for Marijuana DUI Charges in Illinois

Driving under the influence of cannabis is not a minor traffic matter—it is a serious criminal charge. The law is still evolving, and prosecutors are pushing aggressively for convictions even when the evidence is weak. Without a skilled defense attorney, you may face jail time, lose your driver’s license, and carry the stigma of a criminal record.

We have spent decades defending individuals charged with marijuana-related DUIs in Chicago and surrounding counties. We understand the flaws in the science behind THC testing and how to challenge improper procedures, unreliable field sobriety results, and violations of your constitutional rights.

A mistake people often make is thinking they can explain their way out of a charge, only to say something incriminating during questioning or waive important defenses. Others believe a public defender will have the time and resources to mount a thorough defense—but in reality, many are overloaded with hundreds of cases. You need someone with the time and experience to build a winning strategy tailored to your case.

Choose The Law Offices of David L. Freidberg

Our firm has successfully represented clients facing cannabis-related DUI charges throughout Chicago, Cook County, DuPage County, Will County, and Lake County. We have an in-depth understanding of Illinois DUI laws and the prosecutorial tactics used in cannabis cases. When your future is on the line, trust a law firm with a track record of success.

When You Need a Fighter, Call Us

Whether you’re charged in downtown Chicago, Skokie, Maywood, Bridgeview, or Rolling Meadows, we’re ready. We appear regularly in courtrooms throughout Cook, DuPage, Will, and Lake Counties. And we don’t treat aggravated speeding as just another moving violation.

If you were arrested in Chicago, protect your future by contacting The Law Offices of David L. Freidberg. We have decades of experience handling DUI cases in Illinois. Our firm is available 24/7 to provide the legal defense you deserve.

Contact us today at (312) 560-7100 or toll-free at (800) 803-1442 for a free consultation. We’re available 24/7 to serve clients throughout Illinois, Cook County, DuPage County, Will County, and Lake County.