Marijuana and DUI in Illinois: What You Need to Know

Driving under the influence doesn’t just apply to alcohol. In Illinois, cannabis use can also lead to a DUI charge, even if marijuana is legal in the state. For many drivers, this can come as a surprise.

Whether you’re a medical cardholder, recreational user, or simply someone pulled over after legally using cannabis, it’s important to understand how DUI laws apply. The consequences can be just as serious as an alcohol-related offense.

The criminal defense attorneys at Hirsch Law Group help people across Illinois navigate these complex cases. Here’s what to know if you’re facing (or hoping to avoid) a marijuana-related DUI.

How Illinois Law Defines a Marijuana DUI

Illinois law prohibits operating a vehicle while impaired by cannabis. But unlike alcohol, where the legal limit is .08 BAC, marijuana impairment is harder to measure, and that makes the law more complicated.

You can be charged with a cannabis DUI in two primary ways:

• Per Se Violation: If a chemical test shows 5 nanograms or more of THC per milliliter of blood (or 10 nanograms per milliliter in other bodily fluids), it’s considered a DUI, even if you weren’t showing signs of impairment.
  
• Impairment-Based DUI: Even if your THC level is below those limits, you can still be charged if an officer believes your driving was impaired due to marijuana use.

This means you could be charged based on a combination of factors, including officer observations, field sobriety tests, and toxicology results.

Is It Still DUI If I Used Cannabis Legally?

Yes. Legal use does not mean you can drive under the influence. That applies to both recreational users and individuals with a valid medical cannabis card.

Illinois law makes it clear: you can legally consume cannabis, but you cannot operate a motor vehicle if it impairs your ability to drive safely.

Medical users may face fewer issues with per se violations, but they can still be charged if they appear impaired while driving. And if officers find larger amounts of cannabis during the stop, you could also face separate charges like possession with intent to deliver or cannabis trafficking, both of which carry serious penalties in Illinois.

Penalties for a Marijuana DUI

The penalties for a marijuana DUI are similar to those for alcohol-related offenses:

• First offense: Class A misdemeanor, up to 1 year in jail, $2,500 fine, and license suspension
• Second offense: Mandatory minimum 5-day jail sentence or 240 hours of community service
• Repeat offenses: Felony charges, longer license suspensions, and possible prison time

Additionally, you may be required to complete a drug treatment program, undergo regular testing, and install a breath-alcohol ignition device (even though it doesn’t detect cannabis).

Field Sobriety Tests and THC

Unlike alcohol, THC does not have a predictable impairment curve. You can test positive for THC long after the effects have worn off, especially with frequent use. This makes field sobriety tests and officer observations a much bigger part of marijuana DUI cases.

In court, this can raise questions:

• Was the driver actually impaired, or just testing positive from earlier use?
• Were the field sobriety tests properly conducted?
• Did the officer have reasonable suspicion or probable cause?

An experienced lawyer will know how to challenge the officer’s observations, question the reliability of field sobriety tests, and identify weaknesses in the state’s evidence that could lead to reduced charges or a dismissal.

License Suspension After a Cannabis DUI

Like alcohol-related charges, marijuana DUIs can lead to both criminal penalties and administrative action. That includes a Statutory Summary Suspension, which kicks in if you:

• Refuse chemical testing
• Fail a drug test showing THC above legal limits

You have just 46 days from your arrest to challenge this suspension through a formal hearing. Acting quickly gives your attorney more time to review the evidence and file a proper petition.

Why Legal Representation Makes a Difference

Marijuana DUI cases are rarely straightforward. The science is still evolving, and the way law enforcement tests for impairment is often subjective. Having an experienced defense attorney means:

• Reviewing the legality of the traffic stop
• Challenging the reliability of field sobriety tests
• Questioning the THC test method and timing
• Arguing for reduced charges or alternative sentencing options

If your case also involves a separate charge, like possession, a well-rounded legal strategy becomes even more important.

Protect Your Future After a Marijuana DUI

Getting pulled over after using cannabis (legally or not) can quickly turn into a high-stakes situation. In Illinois, marijuana DUIs carry serious penalties, especially if it’s not your first time in trouble with the law.

If you’re facing charges, the best thing you can do is stay silent, avoid making statements to police, and contact a defense attorney as soon as possible. The attorneys at Hirsch Law Group are here to help you understand your rights, review your case, and build a strong defense.

FAQ: Marijuana and DUI in Illinois

1. Can I get a DUI in Illinois if I used marijuana legally?
Yes. Even though recreational and medical cannabis are legal in Illinois, it’s still illegal to drive while impaired. If an officer believes you’re under the influence of marijuana, you can be charged with a DUI, even if your use was legal.

2. How does Illinois determine if I’m too high to drive?
Illinois uses a combination of THC blood levels and signs of impairment. A blood test showing 5 nanograms of THC per milliliter (or more) can trigger a DUI charge. But even if you’re below that limit, you could still be charged based on driving behavior and officer observations.

3. Can I refuse a drug test during a traffic stop?
You can refuse, but doing so will likely result in a Statutory Summary Suspension of your license. For a second refusal, the suspension could last up to three years. Refusal may also limit your options for challenging the case later.

4. How long does THC stay in your system?
THC can remain in your system for days or even weeks, especially for regular users. However, the presence of THC doesn’t always mean you were impaired while driving. That’s why these cases often depend on more than just the test results.

5. What are the penalties for a marijuana DUI in Illinois?
Penalties vary based on your record. A first offense may result in up to a year in jail, a $2,500 fine, and license suspension. Repeat offenses carry steeper consequences, including felony charges and possible prison time.

6. Will I lose my license after a marijuana DUI?
You could. If you fail or refuse a drug test, Illinois law allows for an automatic license suspension. You have 46 days from your arrest to request a hearing to challenge it. Acting quickly gives you more options for protecting your license.