Arizona Court Rules ADOT Can’t Suspend Your License for THC Metabolites Alone — Kirsten v. ADOT Explained
By Gordon Thompson, Arizona DUI & Criminal Defense Attorney | Licensed in Arizona Since 1982
If you’ve been told your driver’s license is being suspended because a blood test found THC metabolites in your system — even though you weren’t impaired and may not have used marijuana in days or weeks — a new Arizona Court of Appeals decision may change everything about your case.
In Kirsten v. Arizona Department of Transportation, Motor Vehicle Division, decided October 1, 2024, Division One of the Arizona Court of Appeals ruled that ADOT cannot administratively suspend a driver’s license based solely on the presence of THC metabolites, without proof that the driver was actually impaired. This is a significant decision for anyone facing an MVD suspension tied to marijuana use, and as a Phoenix DUI attorney who has spent 47 years defending Arizona drivers, I want to walk you through exactly what happened, what it means, and what it does not mean.
What Happened in Kirsten v. ADOT
In October 2022, a Sedona police officer pulled Aaron Kirsten over for speeding. The officer observed bloodshot eyes, slurred speech, and unsteadiness, and a preliminary breath test showed a blood alcohol content of 0.083. Kirsten was arrested for DUI. A later blood draw showed his actual BAC at 0.063 — below Arizona’s legal presumption threshold of 0.08 — but the blood also tested positive for 11 nanograms per milliliter of THC.
ADOT suspended Kirsten’s license for 90 days. At his administrative hearing, Kirsten testified he had not used marijuana within 24 hours of the stop, and his witness, a chiropractor and nurse practitioner, testified that THC can remain detectable in blood for weeks after use — long after any impairment has ended. The Administrative Law Judge upheld the suspension anyway, ruling that the state only needed to show metabolites were present, not that Kirsten was impaired. The superior court agreed, finding that the legislature intended “zero tolerance” for any drug metabolites behind the wheel.
Kirsten appealed, and the Court of Appeals reversed.
Why the Court Sided With Kirsten
The court’s reasoning centered on Proposition 207, the Smart and Safe Arizona Act, which Arizona voters passed to legalize adult marijuana use. The court looked at two provisions working together.
First, A.R.S. § 36-2852(A) says that, notwithstanding any other law, the state cannot penalize a person’s legal marijuana use by limiting “any right or privilege conferred or protected by the laws of this state” — and the court confirmed that a driver’s license is exactly that kind of privilege. The only exception is when a separate statute, A.R.S. § 36-2851(3), specifically allows it — and that statute only allows penalties for driving while “impaired to even the slightest degree.”
Second, A.R.S. § 36-2852(B) reinforces this by stating that a person can only be found guilty of driving with cannabis metabolites in their body under A.R.S. § 28-1381(A)(3) if they were “also impaired to the slightest degree.”
Read together, the court held these provisions override the state’s argument that A.R.S. § 28-1385(M) — the MVD suspension statute — allows a license suspension based on metabolites alone. Because ADOT never argued or proved that Kirsten was impaired at the hearing, the suspension could not stand. The court also noted that the state could not raise an impairment argument for the first time on appeal, since it had deliberately litigated the case on the theory that impairment didn’t matter.
The court vacated the superior court’s order and directed that Kirsten’s license suspension be voided entirely.
What This Means for You
If you are facing an Arizona MVD license suspension connected to marijuana, here is the practical bottom line.
You cannot lose your license for THC metabolites alone. If the state’s case against you is built only on a blood test showing cannabis metabolites — with no evidence you were actually impaired while driving — Kirsten gives you a strong legal basis to challenge that suspension.
This does not legalize driving high. Impaired driving is still illegal under Arizona law, and the burden the state must meet is proof of impairment “to the slightest degree,” not full intoxication. If an officer testifies credibly about poor coordination, erratic driving, slurred speech, or other impairment indicators, the state can still win, even with the same blood test results.
This decision applies to the civil MVD suspension process, not necessarily every criminal charge. Kirsten addressed the administrative license suspension under A.R.S. § 28-1385. Criminal DUI charges under A.R.S. § 28-1381 are a separate track, though Proposition 207’s impairment requirement under A.R.S. § 36-2852(B) applies there as well for metabolite-based charges.
Timing matters enormously. Arizona law gives you only 30 days from the date of arrest to request an MVD hearing contesting any license suspension. If that deadline passes, the suspension takes effect automatically and you may lose the chance to raise an argument like the one that won in Kirsten. If you’ve recently been arrested and a marijuana-related suspension is on the table, this is not a deadline you can afford to miss.
How This Affects Your Defense
As someone who has personally handled MVD hearings and DUI defense in Arizona courts for 47 years and represented more than 6,000 clients, I’ve seen firsthand how often these metabolite-based suspensions get pushed through without the state actually proving impairment. Kirsten gives drivers a real tool to push back, but it has to be raised correctly and at the right stage of the case — which is exactly why having an attorney who knows this area of law in detail, and who personally handles every case from the MVD request through hearing or trial, matters.
I limit my practice exclusively to DUI and criminal defense in Arizona, and I appear regularly in Municipal and Justice Courts throughout Maricopa County, Pinal County, and parts of Northern Arizona — including Coconino County, where the Kirsten case originated. If your license has been suspended, or you’ve been arrested for a marijuana-related DUI anywhere in Arizona, this decision may directly affect the outcome of your case.
Call or text (602) 467-3680 for a free consultation, or request a free online consultation today. Every client works directly with me — not a paralegal, not a junior associate — and my flat-fee structure means you know the full cost upfront, with no hidden fees or trial surcharges.
Frequently Asked Questions
Can ADOT suspend my license in Arizona just for having THC metabolites in my blood?
No. Under Kirsten v. ADOT (2024), the state cannot administratively suspend a driver’s license based solely on the presence of THC metabolites in the blood. The Arizona Court of Appeals ruled that Proposition 207 requires the state to show the driver was impaired to at least the slightest degree by marijuana before a license suspension can stand.
Does this mean I can legally drive after using marijuana in Arizona?
No. Driving while impaired to any degree by marijuana remains illegal in Arizona under A.R.S. § 36-2851(3) and A.R.S. § 28-1381. The Kirsten decision does not legalize impaired driving — it only prevents the state from penalizing a driver based on leftover THC metabolites when there is no evidence of actual impairment at the time of driving.
How long does THC stay in your blood after use?
THC and its metabolites can remain detectable in blood for days to several weeks after use, long after any impairment has worn off. This was the core problem the Kirsten case addressed: a positive blood test does not necessarily mean a person was impaired while driving.
What is the difference between an MVD suspension and a DUI criminal charge in Arizona?
An MVD (Motor Vehicle Division) suspension is a separate civil administrative process handled by ADOT that can take away driving privileges, while a DUI charge under A.R.S. § 28-1381 is a criminal case handled in court. Kirsten v. ADOT specifically addressed the administrative MVD suspension process under A.R.S. § 28-1385, not the criminal DUI statute directly — though both now require proof of impairment for marijuana-related cases under Proposition 207.
What should I do if my license was suspended for a marijuana-related DUI in Arizona?
Act quickly. Arizona law gives you only 30 days from arrest to request an MVD hearing to contest a license suspension, and the Kirsten decision is a strong new legal argument if your suspension was based only on THC metabolites without evidence of impairment. Speak with an experienced Arizona DUI attorney immediately to evaluate whether this ruling applies to your case.
This blog post is for informational purposes only and does not constitute legal advice. Every DUI case involves unique facts, and the outcome of any case depends on the specific evidence and circumstances involved. For advice about your specific situation, contact Gordon Thompson at (602) 467-3680 for a free consultation.
Page authored and reviewed by Gordon Thompson, Arizona State Bar licensed attorney since 1982. Last updated June 2026.