Yes, you can be charged with DUI for marijuana in Arizona, even though adult recreational use is legal. Arizona law prohibits driving while impaired to the slightest degree by marijuana, and it also restricts driving with certain drugs in your system. Blood testing, officer observations, and drug recognition evaluations are the main evidence. Courts have recognized important limits, including that an inactive marijuana metabolite alone does not prove impairment.
Since Proposition 207 legalized adult use in 2020, many drivers in Phoenix, Scottsdale, and across the Valley assume marijuana DUI is no longer a concern. Legalization did not change the rule against impaired driving, and police continue to make these arrests.
The Main Ways Arizona Charges a Marijuana DUI
| Theory | What the State Must Show | Common Evidence |
|---|---|---|
| Impaired to the slightest degree | Marijuana impaired your ability to drive, even slightly | Driving behavior, field tests, officer observations, and a drug evaluation |
| Drug in the body | A prohibited drug or its active form was present in your system while driving | Blood test results |
The penalties for a first marijuana DUI are generally similar to those for a first alcohol DUI, including jail, fines, license consequences, and screening and classes. Our page on penalties for DUI charges in Arizona explains the range.
Why THC Testing Is Complicated
Unlike alcohol, THC does not have a widely accepted per se limit that proves impairment. Active THC levels can fall quickly after use, while inactive metabolites can remain in the body for days or weeks, especially in regular users. That means a positive blood test does not necessarily show a person was impaired at the time of driving.
The Arizona Supreme Court has addressed these issues in State ex rel. Montgomery v. Harris (2014), the court held that the inactive metabolite of marijuana alone could not support a DUI charge under the drug-in-the-body theory. In Dobson v. McClennen (2015), the court recognized that medical marijuana cardholders could raise a defense by showing the concentration was too low to cause impairment.
How Police Build a Marijuana DUI Case
- Observations of driving, such as weaving or slow reaction
- The odor of marijuana and statements about recent use
- Standardized field sobriety tests
- An evaluation by a drug recognition expert officer
- A blood draw, often under a warrant if the driver refuses
Each of these steps can be challenged. Field sobriety tests were designed mainly for alcohol, and their reliability for marijuana impairment is disputed. Drug recognition evaluations involve subjective judgments that can be questioned on cross-examination.
Common Defenses
- The stop lacked reasonable suspicion.
- The blood draw was taken without a valid warrant or consent.
- Blood testing procedures, storage, or chain of custody were flawed.
- The test showed only inactive metabolites.
- Observed driving behavior had another explanation, such as fatigue or road conditions.
- For medical cardholders, the concentration was too low to cause impairment.
What to Do if You Are Stopped
Stay calm and polite, provide your license, registration, and insurance, and avoid volunteering details about when or how much you used. You can decline to answer questions about recent use without being rude. Field sobriety tests are generally voluntary, though refusing a chemical test after arrest carries separate consequences under Arizona’s implied consent law. Write down everything you remember about the stop as soon as you can, including the time, the officer’s statements, and what tests were performed.
Your Driver’s License
A marijuana DUI arrest can trigger an administrative license suspension separate from the criminal case. If you received MVD paperwork, the deadline to request a hearing is short, often 30 days. Missing it can lead to a suspension regardless of what happens in court. First-offense defense options are covered on our first-time DUI offense page.
Frequently Asked Questions
Can you get a DUI for weed in Arizona?
Yes. Driving while impaired to the slightest degree by marijuana is illegal, even though adult use is legal.
Is there a legal THC limit for driving in Arizona?
There is no widely accepted per se THC level that proves impairment, which makes testing evidence more complex.
Can a blood test from days after use lead to a DUI?
Inactive metabolites alone cannot support a DUI charge, according to the Arizona Supreme Court.
Do medical marijuana cardholders have a defense?
Cardholders may be able to show their THC concentration was too low to cause impairment.
Are marijuana DUI penalties the same as alcohol DUI penalties?
A first marijuana DUI generally carries penalties similar to a first alcohol DUI.
Talk to an Arizona Marijuana DUI Lawyer
The Law Office of Joshua A. Lopez defends marijuana and drug DUI charges across Scottsdale, Phoenix, and the Valley. When you call, we will ask about the stop, any testing, and your court date, then explain how the evidence may be challenged and what to do about your license. Learn more about our Phoenix DUI lawyer services.
