For Illinois residents who rely on medical cannabis, the law provides safe, legal access to relief. But despite having a valid medical marijuana card, patients are still being arrested and charged with DUI every day—simply for driving after using their legally prescribed medication. This harsh reality has left many wondering: Can you really be charged with DUI in Illinois for driving on medical marijuana?
The answer is yes. While the law allows for medical marijuana use, it does not allow you to drive if law enforcement believes you’re impaired—even slightly. And because marijuana affects individuals differently, officers often rely on subjective signs of impairment rather than objective proof.
If you’re facing marijuana-related DUI charges, it’s critical to understand your rights, the legal process, and the value of having a skilled defense attorney on your side. Being a registered patient does not automatically protect you from prosecution, but it does open the door to potential legal defenses that could save your license, your record, and your freedom.
Illinois Law on Marijuana and Driving: Where Cardholders Stand
Cannabis laws in Illinois have evolved quickly, with both recreational and medical use now legal. But when it comes to driving, the rules are strict—and often confusing.
Illinois law under 625 ILCS 5/11-501(a)(7) prohibits driving with certain levels of THC in your system. For non-medical users, having 5 nanograms or more of THC per milliliter of blood (or 10 nanograms in other bodily fluids) within two hours of driving is enough for a DUI charge—even without proof of actual impairment.
For registered medical marijuana patients, the state makes an exception to these “per se” limits. If you’re legally authorized to use cannabis, you won’t be automatically charged just because a blood test shows THC in your system.
However, the law still prohibits driving while impaired, regardless of whether your marijuana use was legal. If an officer believes your ability to drive is affected—even mildly—by cannabis, they can arrest you. This makes every case highly subjective and places the burden on the defendant to challenge the officer’s assumptions and testing.
What Does “Impairment” Really Mean?
Unlike alcohol, where a .08 BAC provides a clear threshold for impairment, marijuana has no such agreed-upon standard. THC affects users in highly individual ways. Factors like frequency of use, metabolism, and tolerance levels can cause THC to linger in your system long after the high has worn off.
This is where things get complicated. An officer may base their arrest on field sobriety tests or personal observations—like bloodshot eyes, slow responses, or the smell of marijuana. But none of these symptoms proves you were too impaired to drive safely. That’s where the defense comes in.
What Happens If You’re Pulled Over?
If you’re a registered cardholder stopped by police, you must present your driver’s license and proof of insurance. If the officer suspects you’re under the influence of marijuana, you may be asked to perform field sobriety tests. Unlike drivers without a medical card, you are required by Illinois law to perform these tests under 625 ILCS 5/11-501.2(c)(3).
Refusing the field tests as a medical marijuana patient can result in immediate license suspension. If you complete the tests and are still arrested, you’ll likely be asked to submit to a chemical test—either blood or urine. If you refuse that test, you face a statutory summary suspension of your license, typically for one year.
From there, your case is forwarded to the State’s Attorney. You’ll receive a court date, and your charges will be processed just like any other DUI case—even if your cannabis use was legal and prescribed.
What Penalties Could You Face?
Even a first-time marijuana DUI in Illinois is serious. The charge is typically filed as a Class A misdemeanor, punishable by:
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Up to 364 days in jail
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Up to $2,500 in fines
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Mandatory substance abuse education or counseling
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Driver’s license suspension for 6–12 months
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A permanent criminal record if not resolved through supervision
If the offense involved an accident, child passengers, or a prior DUI, you could face felony charges with much harsher consequences under 625 ILCS 5/11-501(d).
Medical marijuana patients are often surprised to find out that a conviction for DUI—even when using their prescription legally—can disqualify them from future driving relief programs, increase their insurance rates, and negatively affect employment.
How Prosecutors Build These Cases
Marijuana DUI cases are often based on observation rather than hard science. Since THC can stay in your system for days or even weeks, prosecutors can’t always rely on blood levels to show impairment.
Instead, they focus on:
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The officer’s description of your driving (e.g., weaving, drifting)
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Your behavior at the scene (e.g., slurred speech, delayed responses)
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Field sobriety test performance
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Physical appearance (e.g., red eyes, drowsiness)
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Any admissions you made during the stop (“I used earlier today”)
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Presence of cannabis or paraphernalia in the car
In some cases, they’ll use a Drug Recognition Expert (DRE)—an officer trained to evaluate impairment based on a 12-step protocol. But these evaluations are also subjective and can be challenged in court.
How a DUI Attorney Can Help Defend Your Case
When you’re facing DUI charges involving medical marijuana, the best thing you can do is contact a defense lawyer immediately. Marijuana DUIs are unique, and defending them requires a combination of legal knowledge and scientific insight.
An experienced DUI attorney can:
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Review and challenge the legality of the traffic stop
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File motions to suppress improper field sobriety tests or statements
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Dispute the validity of THC testing and toxicology reports
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Challenge the arresting officer’s conclusions and lack of training
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Present medical explanations for your appearance or behavior
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Argue that THC presence does not equal impairment
A strong defense can mean the difference between a conviction and a case dismissal or reduction to a non-DUI offense. And for many first-time offenders, it could also make you eligible for supervision, avoiding a conviction altogether.
Is It Possible to Avoid a Conviction?
Yes. Many medical marijuana DUI cases end without a conviction—especially if the driver’s conduct was otherwise safe, or the prosecution’s evidence is thin. Possible outcomes include:
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Case dismissed due to lack of evidence
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Charge reduced to reckless driving
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Supervision (avoids a conviction if all conditions are met)
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Not guilty verdict at trial
The earlier your attorney gets involved, the better your chances of securing a favorable outcome. Acting quickly allows your lawyer to file for rescission of the summary suspension, collect evidence, and begin negotiations before the prosecution locks into a theory.
Common Defenses That Work
Some of the most effective defenses in medical marijuana DUI cases include:
1. No Probable Cause for the Stop: If the officer didn’t have a legal reason to pull you over, all evidence obtained during the stop may be inadmissible.
2. No Proof of Impairment: THC in your system is not proof of impairment. The prosecution must show that your ability to drive was actually affected.
3. Field Sobriety Test Issues: These tests were developed for alcohol detection and are often unreliable for marijuana impairment.
4. Officer Bias or Misinterpretation: Physical signs of fatigue, illness, or medication side effects may be mistaken for cannabis influence.
5. Medical Exemptions Misunderstood: Sometimes, officers are unaware of how the law treats medical cardholders. Your rights may have been violated.
Call David L. Freidberg — Defending Medical Marijuana DUI Charges Throughout Chicago
If you’ve been arrested in Chicago for driving after using your medical marijuana prescription, you need an attorney who understands both the science and the law. At The Law Offices of David L. Freidberg, we represent medical marijuana patients throughout Cook County, DuPage County, Will County, and Lake County.
We know the law, the court system, and how to fight DUI charges that lack scientific proof. Whether the goal is suppression of evidence, reduction of charges, or total dismissal, we work with you to protect your freedom and preserve your future.
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.