Understanding a Cannabis DUI

 Posted on January 13, 2026 in DUI

You might be surprised to learn you can be charged with a DUI for cannabis, even though marijuana is legal in Illinois. As of 2026, Illinois still strictly enforces cannabis-related DUI laws across the state, despite legal recreational use. Police can charge someone with a DUI based on cannabis use, even when there are no obvious signs of impairment.

Concerns about this issue are growing. In a statewide survey of Illinois drivers published in March 2025, more than half said the state should be doing more to address cannabis-impaired driving since legalization. If you are facing a drug-related DUI charge, our Elgin, IL drug DUI defense lawyer can help you understand how these charges work and what the state must prove.

Can You Get a DUI for Cannabis in Illinois?

Illinois law allows DUI charges for cannabis in more than one way. A driver does not have to appear impaired or unsafe to be arrested.

Under 625 ILCS 5/11-501, a person may be charged if police believe cannabis affected their ability to drive safely or if chemical testing shows THC above the legal limit. The law treats cannabis DUIs much like alcohol DUIs, even though cannabis does not affect everyone the same way.

What THC Levels Are Illegal While Driving in Illinois?

Illinois uses set THC limits, often called per se limits. Once these limits are reached, the law assumes impairment, even if the driver felt normal at the time.

A driver may face charges if testing shows:

• Five nanograms or more of THC per milliliter of whole blood

• Ten nanograms or more of THC per milliliter of saliva

• A measurable amount of THC detected after a traffic stop

Remember, THC can stay in the body long after its effects wear off, which is why an experienced Kane County criminal defense attorney can often challenge these charges in court.

How Do Police Investigate a Cannabis DUI in Illinois?

Many cannabis DUI cases start with routine traffic stops for issues like lane drifting or inconsistent speed. In Elgin, stops often happen on heavily traveled roads such as Route 20 or Randall Road.

Officers rely on observations, field sobriety tests, and later chemical testing. There is no roadside breath test for marijuana, so evidence is usually collected after the stop, sometimes much later.

Under 625 ILCS 5/11-501.1, Illinois’s implied consent law, drivers are considered to have agreed to chemical testing after a lawful DUI arrest. Refusing testing can lead to license penalties, even if the DUI charge itself is later challenged.

What Defenses Are Common in Illinois Marijuana DUI Cases?

Defenses in cannabis DUI cases often focus on whether the evidence truly shows impaired driving. Because THC can remain in the body for an extended time, test results alone may not prove someone was impaired behind the wheel.

Delays between driving and testing can weaken the state’s case. Field sobriety tests may also be unreliable, since they were designed for alcohol, not cannabis.

Courts also review whether the traffic stop was lawful and whether testing followed proper procedures. Many signs officers rely on can be caused by stress, fatigue, or medical issues rather than cannabis use.

What Penalties Can a Cannabis DUI Lead To in Illinois?

A first cannabis DUI is usually charged as a Class A misdemeanor in Illinois. Penalties depend on the facts of the case and a person’s record.

Possible consequences may include:

• Jail time or court supervision

• Fines and court costs

• Driver’s license suspension or revocation

• Required drug education or treatment programs

Under 730 ILCS 5/5-6-3, judges have wide discretion when setting probation conditions, which often includes treatment even when impairment is disputed.

Schedule a Free Consultation With Our Kane County, IL Drug DUI Defense Attorney

If you are facing a cannabis DUI charge, The Law Office of Brian J. Mirandola can help you better understand your options. Attorney Mirandola brings more than 20 years of experience in criminal law, including seven years as a former Assistant State’s Attorney working in the county prosecutor’s office. That experience provides a valuable perspective on how these cases are charged, reviewed, and challenged in local courts.

Call 847-488-0889 to schedule a free consultation with our Elgin, IL drug DUI defense lawyer and get clear, practical guidance on building your defense.