Overview
A Legal Product, an Arbitrary Number,
and a DUI Charge
Illinois legalized recreational cannabis in 2020 and simultaneously created a per se DUI standard for THC under 625 ILCS 5/11-501(a)(7). The statute sets a limit of 5 nanograms of THC per milliliter of whole blood. Exceed that number, and the violation is established as a matter of law — exactly the way 0.08 works for alcohol. The state does not need to prove you were impaired. It needs to prove the number.
The problem — and the defense opportunity — is that the 5 ng/mL threshold does not track impairment the way 0.08 does for alcohol. Alcohol and THC metabolize through entirely different mechanisms. Alcohol concentration in the blood rises and falls in a predictable, well-documented relationship to impairment. THC does not. THC is fat-soluble, which means it is stored in body tissue and released into the bloodstream over time in patterns that vary dramatically based on frequency of use, body composition, and individual metabolism. A regular cannabis user can have a blood THC concentration above 5 ng/mL hours or days after any meaningful impairment has passed. An infrequent user may be genuinely impaired at concentrations below the threshold.
The scientific community, including the National Highway Traffic Safety Administration, has acknowledged that no reliable per se THC concentration for impairment has been established. Illinois set 5 ng/mL anyway — a legislative judgment, not a pharmacological one. That disconnect between the legal threshold and the science of impairment is the foundation of every serious cannabis DUI defense.
Cannabis DUI cases also frequently involve a simultaneous charge under subsection (a)(4) — the impairment-based drug DUI. When both subsections are charged together, the state is pursuing two independent theories: that the THC number establishes the per se violation under (a)(7), and that the officer's observations and DRE evaluation establish actual impairment under (a)(4). Both charges must be defended independently. Michael McMahon spent years as a DuPage County prosecutor on both sides of these cases. Contact us for a free case review.
Charge Comparison
(a)(7) vs. (a)(4):
Why Both Charges Matter
Cannabis DUI arrests routinely produce charges under both subsections simultaneously. Understanding what the state must prove under each — and how the defenses differ — is essential from day one.
When both charges are filed together and the blood draw result is suppressed or excluded, the (a)(7) charge collapses entirely. The state must proceed solely on (a)(4) and prove actual impairment from observation evidence alone. This is why challenging the blood draw is so consequential in cannabis DUI cases — defeating it eliminates the per se count and forces the state onto a harder theory.
Conversely, when the THC concentration comes back below 5 ng/mL, the (a)(7) count cannot be sustained — but the state will frequently maintain the (a)(4) charge and argue impairment through the DRE evaluation and officer observations. A below-threshold result weakens the state's overall position considerably, but it does not end the case. Both charges must be addressed regardless of where the number lands.
It is also worth understanding what happens when a driver tests positive for both THC and alcohol. In that scenario, the state may charge under (a)(1) for the alcohol BAC, (a)(2) for alcohol impairment, (a)(4) for drug impairment, and (a)(7) for the THC per se count — four separate theories arising from a single traffic stop. Each requires its own analysis, and the combined-substance argument under (a)(4) adds a layer of pharmacological complexity that demands expert attention from the outset.
Penalties and Consequences
What You Face
If Convicted
A conviction under (a)(7) carries the same penalties as any other DUI conviction. The subsection charged does not affect the sentencing range — what matters is the offense count and whether any aggravating factors apply.
Prosecution's Case
How the State Proves
Cannabis DUI
The (a)(7) per se charge lives or dies on the blood draw result. If the number is at or above 5 ng/mL and the draw is admissible, the state rests. That simplicity is also the charge's vulnerability — there is one piece of evidence, and it must survive every challenge to the stop, the consent, the collection procedure, the chain of custody, and the lab analysis. The (a)(4) impairment count, charged alongside it, requires the full range of observational and expert evidence. Both theories must be fully understood.
-
Blood draw result and THC concentration: The toxicology report showing whole blood THC at or above 5 ng/mL is the core of an (a)(7) prosecution. The state must establish that the blood was drawn, preserved, and analyzed in compliance with statutory requirements, that the testing laboratory is properly certified, and that the reported concentration was accurate. Each link in that chain is contestable. The reported number also must reflect the whole blood concentration — not serum or plasma concentration, which are higher and cannot be converted to whole blood equivalents without a valid methodology. Laboratories do not always report this distinction clearly, and it matters for whether the statutory threshold is actually met.
-
Driving behavior before the stop: For the (a)(4) impairment count, the officer's account of the driving that prompted the stop anchors the narrative. Cannabis impairment, when it exists, tends to produce different observable driving behaviors than alcohol — slower reaction times, inconsistent speed, failure to maintain lane position — and those behaviors are not always present even when THC is detectable in the blood. Dashcam footage of the moments before the stop either confirms the officer's account or directly contradicts it. In cannabis cases especially, clean driving footage is among the strongest evidence available to the defense.
-
Officer observations at the vehicle: Bloodshot or red eyes, odor of cannabis, slow or delayed responses, impaired short-term memory indicators, and dry mouth are the most commonly documented cannabis impairment indicators. Each has an innocent explanation. Bloodshot eyes are consistent with allergies, fatigue, and contact lens use. Cannabis odor establishes prior exposure, not current impairment. Delayed responses can reflect nervousness at a traffic stop at night. Body cam footage captures the same interaction from a different angle and frequently tells a different story than the written police report — particularly regarding how coherent and responsive the driver actually was.
-
Drug Recognition Expert evaluation: If a DRE was called to conduct a post-arrest examination, the 12-step protocol evaluation will be part of the prosecution's impairment case under (a)(4). For cannabis specifically, the DRE protocol looks for elevated pulse, normal blood pressure, dilated pupils in dark conditions, and increased body temperature as indicators of cannabis intoxication. The cannabis-specific indicators in the DRE protocol have documented reliability limitations, and the examination must be conducted in precise conformance with training standards. Every deviation, every finding with an innocent alternative explanation, and every gap between what the DRE documented and what the body cam shows is a defense opportunity.
-
Field sobriety test results: Standardized FSTs were designed and validated against alcohol impairment, not cannabis impairment. The scientific basis for using HGN, Walk-and-Turn, and One-Leg-Stand to detect cannabis-specific impairment is significantly weaker than their use in BAC cases. Cannabis does not produce nystagmus the way alcohol does, which limits the diagnostic value of HGN in cannabis cases specifically. The state may supplement standardized FSTs with additional modified Romberg balance tests or other protocol elements. All of them are subject to the standard administration deviation challenges and, in cannabis cases, the additional challenge that their predictive validity for this specific substance is genuinely disputed in the scientific literature. See our full FST defense analysis.
Defense Strategies
How We Fight
This Charge
Traffic Stop
If the officer lacked reasonable suspicion to initiate the stop, all evidence gathered during it — the blood draw, FST results, DRE evaluation, and all observations — must be excluded under the Fourth Amendment. A successful suppression motion eliminates both the (a)(7) per se count and the (a)(4) impairment count simultaneously. In cannabis DUI cases, stops are sometimes initiated on pretextual minor traffic violations when the officer suspected cannabis use based on a smell or observation before the stop was legally justified. We evaluate every stop for suppression grounds as the first order of business. Learn more about traffic stop challenges.
and Chain of Custody
The (a)(7) per se charge rests entirely on the blood draw result. We examine every link in the chain: whether consent was voluntarily given or a warrant was required, the qualifications of the person who drew the blood, the type and condition of the collection tube used, preservative and anticoagulant requirements, refrigeration and storage documentation, the lab's certification status, and the specific testing methodology employed. A compromised sample or a flawed collection procedure produces an unreliable concentration result — and an unreliable result cannot establish a per se violation beyond a reasonable doubt. We also verify that the reported concentration reflects whole blood specifically, not serum or plasma, as the statute requires.
of the 5 ng/mL Threshold
The 5 ng/mL limit was a legislative decision, not a pharmacological one. The scientific literature — including research cited by NHTSA itself — does not establish a reliable THC blood concentration above which impairment consistently occurs. Regular cannabis users frequently test above 5 ng/mL well after any impairing effects have resolved, while infrequent users may be meaningfully impaired below the threshold. We retain forensic toxicologists to present this evidence to the jury and to challenge the prosecution's expert on the scientific basis for treating the per se limit as a reliable indicator of actual impairment at the time of driving. This does not mean the charge is dismissed — but it creates substantial reasonable doubt about what the number actually proves.
Does Not Equal Impairment
THC is fat-soluble and accumulates in body tissue with regular use. It is released back into the bloodstream over time in ways that have no reliable relationship to when cannabis was last consumed or whether any impairment is present. A regular user may test at 7 or 8 ng/mL twenty-four hours after last using cannabis, with no meaningful impairment at all. We retain forensic toxicologists to testify about individual variation in THC metabolism, the documented absence of a reliable concentration-impairment relationship, and whether the specific concentration in this case is pharmacologically consistent with the time of last use that the evidence supports. In many cannabis DUI cases, this expert testimony is the most important work in the defense.
the Impairment Narrative
Cannabis DUI cases often hinge on the contrast between what the officer wrote in the report and what the body cam and dashcam actually show. Officers are trained to document impairment indicators, and they typically do — but the video record frequently shows a driver who was coherent, responsive, and in control of the vehicle. We review dashcam and body cam footage in detail, develop the alternative explanation for every documented observation, and identify every inconsistency between the officer's written account and what the footage shows. In cannabis cases where the driving was clean and the video shows a composed interaction, the impairment narrative the prosecution builds in the report is often directly contradicted by the evidence they gathered themselves.
to Avoid a Conviction
When defeating the charge entirely is not achievable, first-offense court supervision avoids a conviction on your permanent record, preserves your license, and keeps all future options open. Supervision under §11-501(c)(1) is available once per lifetime for any DUI charge regardless of subsection. Successfully completing the supervision period results in a dismissal, not a conviction. The difference between supervision and a cannabis DUI conviction is permanent — and in an era where cannabis is legal and social attitudes are shifting, a conviction still carries lasting consequences for employment, housing, and professional licensing that a handled supervision does not.
Legal Process
What Happens After
This Arrest
You are arrested and asked to submit to a blood draw. Breathalyzers do not detect THC, so blood is the standard chemical test in cannabis DUI cases. If you submitted to the draw and the result comes back at or above 5 ng/mL, a Statutory Summary Suspension is triggered. You are issued a Notice of Statutory Summary Suspension that serves as your temporary driving permit for 45 days. Note that the suspension notice is typically issued before the toxicology results return — the officer issues it based on the evidence of drug use at the scene. Contact an attorney immediately. The 90-day deadline to contest the suspension and the window for preserving dashcam footage both begin running at the moment of arrest.
We immediately send preservation demands to the arresting agency for dashcam footage, body cam footage, and any in-car recording. We request the arrest report, the DRE evaluation documentation and certification records if a DRE examination was conducted, the blood draw chain of custody records, and the toxicology lab report with full methodology documentation. Dashcam footage at many agencies is overwritten within 30 days. In cannabis DUI cases specifically, the video of the driving before the stop and the field interaction is often the most valuable defense evidence in the file — and it disappears quickly without a preservation demand on record.
Your Statutory Summary Suspension takes effect on day 46. You have 90 days from the arrest date to file a Petition to Rescind the suspension — after day 90, that right is permanently lost. In cannabis cases, the suspension challenge may focus on whether the blood draw was properly obtained, whether consent was voluntary, whether the officer had lawful grounds to request the draw, and whether the testing result met the statutory requirements. A granted petition restores your driving privileges independent of how the criminal case resolves. Learn more about the suspension process.
Your first court appearance is arraignment at the DuPage County Courthouse, 505 N. County Farm Road, Wheaton. You enter a not-guilty plea. Toxicology results in cannabis cases typically take 6 to 10 weeks to return from the lab, which means the prosecution's central evidence under the (a)(7) count may not be in hand at arraignment. A pretrial conference is scheduled 4 to 8 weeks out. Do not accept any plea offer before the toxicology report is reviewed by an experienced DUI attorney and, where the results warrant it, an independent forensic toxicologist. The prosecution's early assessment of a cannabis DUI case is almost always made without the benefit of a careful pharmacological analysis of what the number actually proves.
In cannabis DUI cases with results near the 5 ng/mL threshold or with facts supporting a detection-versus-impairment argument, we retain a forensic toxicologist to review the lab report, analyze the methodology, and assess whether independent testing of the preserved blood sample is warranted. We file suppression motions where grounds exist and prepare for the suspension hearing. In cases where the DRE evaluation is a primary pillar of the (a)(4) count, we assess whether the examination was conducted according to protocol and whether the methodology is subject to challenge. This expert and motion phase is where cannabis DUI cases are frequently won before they ever reach trial.
First-offense cannabis DUI cases in DuPage County typically resolve through one of three paths: dismissal following a successful suppression motion or successful challenge to the blood draw or toxicology evidence, court supervision by agreement after a plea, or trial. Cannabis cases are increasingly trial-viable when the driving video was clean, the observational impairment evidence is weak, and a forensic toxicologist can effectively present the science of THC metabolism to a jury. We evaluate every case for trial viability from day one and present our honest assessment of every available path before any decision is made.
FAQ
Cannabis DUI:
Common Questions
Illinois legalized recreational cannabis in January 2020 and simultaneously enacted the 5 ng/mL per se THC standard. Legal purchase and lawful consumption do not exempt you from the DUI statute — the same way a legal drink at a bar does not exempt you from alcohol DUI if you exceed 0.08. The legality of the substance and the legality of driving after using it are entirely separate questions under Illinois law. What makes cannabis DUI legally and scientifically distinct from alcohol DUI is that the 5 ng/mL threshold has no reliable pharmacological relationship to actual impairment — but the per se charge does not require the state to prove impairment. It requires the state to prove the number.
Yes — and this is one of the most significant problems with the 5 ng/mL per se standard. THC is fat-soluble and stored in body tissue. Unlike alcohol, which metabolizes predictably and clears the blood in hours, THC can remain detectable in whole blood at concentrations above 5 ng/mL for 24 hours or more in regular users, even when no meaningful impairment is present. Infrequent users typically show faster concentration decline. The time between last use and the blood draw, combined with your individual usage pattern and metabolism, determines where the concentration lands — but the statute does not care. If the number is at or above 5 ng/mL at the time of driving, the per se violation is established regardless of when you actually used. This is the core scientific injustice of the statute and the core argument that a forensic toxicologist makes on your behalf at trial.
A below-threshold result defeats the (a)(7) per se count, but the state can still pursue an (a)(4) impairment-based charge. Under (a)(4), the state must prove you were actually under the influence of cannabis to a degree that rendered you incapable of driving safely — and any detectable THC concentration can be offered as supporting evidence for that theory alongside officer observations and DRE findings. A below-threshold result is genuinely powerful mitigation and makes the (a)(4) argument substantially harder for the state to sustain, particularly when the driving was normal and the video does not show meaningful impairment indicators. But it does not end the case. Both the THC result and the impairment theory must be addressed.
Yes, but refusal triggers the same Statutory Summary Suspension consequences as refusing a breathalyzer in an alcohol case — and potentially longer suspension periods. Refusing also eliminates the (a)(7) per se count, since without a blood draw result the state cannot establish the THC concentration. The state would then rely entirely on an (a)(4) impairment theory using the officer's observations and DRE evaluation. Additionally, police may obtain a warrant for a compelled blood draw if probable cause exists and time permits — and if a warrant was issued and the draw proceeded over your refusal, the admissibility of that result depends on whether the warrant was properly supported and executed. The consequences of refusing a blood draw in a cannabis DUI stop must be evaluated case by case.
Subsection (a)(7) is the per se cannabis charge — the state proves your whole blood THC was at or above 5 ng/mL and rests. No proof of actual impairment is required. Subsection (a)(4) is the impairment-based drug DUI — the state must prove you were actually under the influence of cannabis to a degree that rendered you incapable of driving safely, using officer observations, DRE findings, and field sobriety test performance. Both carry identical penalties. The critical practical difference is that (a)(7) collapses entirely if the blood draw is suppressed or the THC result fails to meet the threshold. (a)(4) survives those outcomes and must be defended on its own merits. You cannot treat a dual-count cannabis DUI as a single charge — each theory requires independent analysis and strategy.
Yes, on a first offense. Court supervision is available for a first-offense cannabis DUI under (a)(7) on the same terms as any other first-offense DUI misdemeanor. It is a non-conviction disposition that avoids license revocation and keeps your record clean upon successful completion of the supervision period. Supervision is available only once per lifetime for any DUI charge — a prior DUI of any kind, including an alcohol DUI, uses up your one lifetime supervision opportunity. If supervision is available to you, pursuing it rather than accepting a conviction is almost always the right outcome when defeating the charge entirely is not achievable.