Can You Be Charged with DUI in Illinois for Driving on Medical Marijuana?

Chicago is no stranger to evolving cannabis laws. With the state of Illinois legalizing recreational marijuana and expanding access to medical marijuana through licensed cardholders, many residents believe that having a medical card protects them from prosecution. Unfortunately, that assumption can lead to serious legal consequences.

Even if you’re a licensed patient using marijuana for legitimate medical reasons, you can still be charged with DUI in Illinois under the state’s current laws. The fact that your use was lawful under the Compassionate Use of Medical Cannabis Pilot Program Act does not shield you from being arrested or prosecuted for driving under the influence.

Police officers in Chicago and throughout Cook County continue to make arrests based on perceived cannabis impairment—often without a clear chemical test result or evidence of actual intoxication. If you’ve been charged with DUI while driving on medical marijuana, your next steps will make all the difference in the outcome of your case.

Understanding How Illinois DUI Law Applies to Cannabis

Illinois law treats cannabis-impaired driving similarly to alcohol-related DUI. Under 625 ILCS 5/11-501(a)(7), a person can be charged with DUI if they operate a motor vehicle while there is a tetrahydrocannabinol (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.

However, under 625 ILCS 5/11-501.2(c), medical marijuana patients are exempt from per se THC thresholds. That means if you’re a registered medical cannabis user in Illinois, simply having THC in your system above the legal limit does not automatically mean you’re guilty of DUI. But that exemption comes with a major caveat—the law still prohibits driving while impaired by marijuana, regardless of whether your use was legal.

This means prosecutors don’t have to prove how much THC was in your blood. Instead, they’ll focus on whether your driving behavior or appearance suggested you were impaired. The DUI becomes a Class A misdemeanor, which carries a sentence of up to one year in jail, a fine of up to $2,500, and mandatory license suspension.

More serious penalties can apply if the DUI involved an accident, bodily injury, or prior offenses. Repeat cannabis DUIs can be prosecuted as felonies under 625 ILCS 5/11-501(d), especially if a prior conviction is on your record or if aggravating circumstances are present.

What Happens After a Cannabis-Related DUI Arrest in Chicago

If you’re pulled over in Chicago and suspected of driving under the influence of marijuana, the police officer will initiate a DUI investigation. This may include questioning, observation of physical symptoms (such as red eyes or slow speech), and possibly asking you to perform field sobriety tests. If you’re a medical marijuana cardholder, you are required by law to submit to field sobriety testing under 625 ILCS 5/11-501.2(c)(3)—a key difference from drivers without a card.

If the officer believes you’re impaired, you’ll be placed under arrest and may be taken for chemical testing—usually a blood or urine test. While medical cardholders are exempt from per se THC limits, chemical results may still be used to suggest recent use. If you refuse chemical testing, you could face a statutory summary suspension of your driver’s license under 625 ILCS 5/11-501.1.

Once charged, you’ll be required to appear at the Daley Center or another Cook County courthouse depending on where the arrest occurred. The prosecution may charge you under the general impairment statute or argue that your driving ability was affected by the recent use of marijuana, despite your valid prescription.

Evidence Used in Cannabis DUI Cases

Cannabis DUI cases can be especially complex because they often lack the kind of definitive chemical evidence present in alcohol-related DUI charges. Prosecutors and police rely heavily on observational and circumstantial evidence to build their case.

This evidence often includes:

• Field sobriety test performance
• Officer observations (e.g., slurred speech, bloodshot eyes, odor of marijuana)
• Video footage from dashcams or body-worn cameras
• The driver’s statements or admissions about recent use
• Blood or urine test results showing THC presence
• Drug Recognition Expert (DRE) evaluations if available

Unfortunately, many of these indicators are subjective, and THC can remain in the body long after impairment has worn off. That’s why defending these cases requires a deep understanding of toxicology, marijuana pharmacology, and the flaws in current drug testing protocols.

How the Criminal Trial Process Works in Illinois for Marijuana DUI

The legal process in a marijuana DUI case begins with your arraignment, where formal charges are read. A plea is entered, and the judge may set conditions of bond, including drug testing or supervision. The next phase involves pretrial hearings, where your attorney may file motions to suppress evidence or request disclosure of the evidence against you.

Your attorney will have the opportunity to challenge whether the stop was legal, whether the officer had probable cause to arrest you, and whether the testing process was properly conducted. In some cases, key evidence can be excluded, leading to dismissal or reduction of charges.

If the case proceeds to trial, the prosecution will present its evidence of impairment. This may include video, lab results, and testimony from the arresting officer. Your attorney will cross-examine witnesses, introduce expert testimony, and highlight reasonable doubt.

A conviction will result in criminal sentencing and administrative penalties from the Illinois Secretary of State, including a driver’s license suspension or revocation. Additionally, the consequences of a DUI conviction can extend far beyond the courtroom.

Why You Shouldn’t Handle a Marijuana DUI Alone

Marijuana DUI cases—especially those involving medical cannabis—are legally and scientifically complicated. THC affects everyone differently, and there is no scientifically agreed-upon threshold for impairment like there is with alcohol. That puts you at a disadvantage unless you have someone on your side who understands how to attack the state’s evidence and build a persuasive defense.

A qualified DUI defense attorney can:

• Challenge the officer’s field sobriety procedures
• Discredit the interpretation of test results
• File motions to suppress unlawfully obtained evidence
• Present medical or physical conditions that explain observed behavior
• Cross-examine police officers and toxicologists effectively

Without an attorney, you could lose your license, pay thousands in fines, and carry a permanent conviction—despite having done everything legally to manage your condition through medical marijuana.

Potential Legal Defenses to Medical Marijuana DUI Charges

Your defense may vary depending on the specific facts of your case, but some of the most effective legal arguments include:

• No actual impairment: Evidence of THC in your system is not proof of impairment. If the officer’s observations don’t hold up under scrutiny, the charge may not stand.
• Improper testing procedures: If the blood or urine sample was mishandled, the results could be thrown out.
• Unlawful stop: If the initial traffic stop was not based on reasonable suspicion, all subsequent evidence may be suppressed.
• Medical condition misinterpreted as impairment: Fatigue, anxiety, neurological conditions, or prescription medications may explain some of the officer’s claimed observations.
• Lack of probable cause: If you were arrested solely on the basis of your cardholder status or the smell of marijuana, your rights may have been violated.

A tailored legal strategy can make a major difference in the outcome of your case, especially in marijuana DUI prosecutions where proof of impairment is anything but clear-cut.

Choosing the Right Criminal Defense Attorney in Chicago

When facing a marijuana DUI in Chicago, you need a defense attorney who understands both Illinois DUI law and the emerging legal issues surrounding cannabis use. Look for someone who regularly practices in Cook County, understands the local court system, and has experience with both chemical testing procedures and suppression motions.

Avoid attorneys who treat DUI as a quick plea. Instead, choose someone who will dig into the evidence, meet with you personally, and commit to doing everything possible to fight your charges.

Questions to Ask in Your Free Consultation

Before hiring an attorney, make sure you ask:

• Have you handled marijuana DUI cases involving medical cardholders?
• What outcomes have you achieved in cases like mine?
• Will you review the lab results and testing procedures for errors?
• How will you approach suppression motions or probable cause challenges?
• How available will you be to answer my questions as the case proceeds?

The answers you receive will help you decide whether the attorney is prepared to protect your rights and guide you through the complexities of Illinois DUI law.

Chicago-Based DUI FAQs

Can I still be charged if I’m a registered medical marijuana patient?
Yes. Illinois law allows police to arrest cardholders if they believe you’re impaired while driving. The medical marijuana exemption only protects you from per se THC limits—it doesn’t prevent DUI charges based on officer observations.

Will I automatically lose my license for a marijuana DUI?
Not automatically. However, if you refuse chemical testing, your license will be suspended. If convicted of DUI, you face a statutory license suspension. Your attorney can help challenge both the criminal and administrative penalties.

Is marijuana impairment measured the same as alcohol?
No. Alcohol impairment is tied to specific BAC levels, but marijuana affects everyone differently. Illinois law does not have a universally accepted THC impairment standard for medical users, which gives your attorney room to challenge the prosecution’s assumptions.

Do field sobriety tests detect marijuana impairment accurately?
Not always. Field tests were developed for alcohol impairment and don’t reliably indicate cannabis effects. In fact, people with certain medical conditions or physical limitations may “fail” these tests while completely sober.

Can I beat the charge if there’s no blood test or drug recognition expert?
Possibly. Without a chemical test or DRE evaluation, the State has to rely entirely on subjective officer observations, which can be challenged in court.

Where will my case be heard in Chicago?
Most DUI cases are heard at the Daley Center or another designated branch of the Cook County Criminal Courts. Your attorney will handle appearances, filings, and negotiations on your behalf.

How soon should I contact an attorney after arrest?
Immediately. The earlier your lawyer gets involved, the more opportunities there are to challenge evidence, file motions, and preserve your driving privileges.

Why You Need the Law Offices of David L. Freidberg

Medical marijuana DUI charges are complex—and the penalties are real. At The Law Offices of David L. Freidberg, we’ve been defending Chicago drivers for decades. We understand the evolving marijuana laws in Illinois and how to protect your rights when you’re accused of impaired driving based on your legal use of cannabis.

Our firm fights aggressively to challenge the evidence, question the arrest, and secure the best possible result. We don’t treat you like a case file—we treat your case like it’s personal, because for you, it is.

Call Now – The Law Offices of David L. Freidberg Is Ready to Help

If you were arrested in Chicago for DUI, 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.