Marijuana Is Legal in Arizona — But You Can Still Get a DUI
If you’ve been arrested or charged with a DUI for marijuana in Arizona, you’re probably confused — and for good reason. After all, recreational marijuana use is legal for adults in our state. So how is it possible to get a DUI if you weren’t drinking and all you did was ingest a legal substance?
I get this question all the time from clients in Tucson and throughout Pima County. The short answer is: yes, marijuana is legal, but driving while impaired by marijuana is not. The law draws a hard line between using cannabis and driving safely — and the penalties for a marijuana DUI can be just as serious as those for an alcohol-related DUI.
Here’s what you need to know if you or someone you care about is facing a marijuana DUI charge in Arizona.
Marijuana DUI in Arizona: What the Law Actually Says
Under A.R.S. § 28-1381(A)(1), it is illegal to drive or be in actual physical control of a vehicle in Arizona while impaired to the slightest degree by any substance — legal or illegal. This includes alcohol, prescription medications, over-the-counter drugs, and yes, marijuana.
There is a separate provision — A.R.S. § 28-1381(A)(3) — that makes it illegal to drive with any drug listed in A.R.S. § 13-3401 or its metabolite in your body. But that particular law has become more nuanced after Arizona legalized recreational marijuana. Now, just having a marijuana metabolite in your system is not automatically enough for a conviction unless the State can prove you were actually impaired.
The State now must prove two things:
That you were impaired to the slightest degree, and
That the impairment was caused by marijuana use.
This is a crucial distinction. Unlike alcohol, where the law has a “per se” limit of 0.08 BAC, there is no equivalent magic number for THC. That makes marijuana DUI cases very fact-specific — and very defensible with the right attorney.
Why Marijuana DUI Cases Are So Confusing
Most people understand that if they blow over a 0.08, they’re going to get a DUI. But with marijuana, it’s not that simple. THC, the active compound in marijuana, doesn’t behave like alcohol in the body. It’s fat-soluble, which means it can stay in your system for days or even weeks after use — long after any actual impairment has worn off.
So you can smoke legally on a Saturday night, get pulled over for something unrelated on a Tuesday, and if the officer suspects you’re high and orders a blood test, THC could still show up. But that doesn’t necessarily mean you were impaired.
The State has to prove causation — that any driving issues were caused by marijuana. That’s a high burden, and many officers simply aren’t trained to make that call properly.
How the State Tries to Prove Impairment
In marijuana DUI cases, prosecutors often rely on a combination of the following:
Officer observations (such as bloodshot eyes, slow responses, “green tongue,” or the odor of marijuana)
Field sobriety tests (FSTs), like walk-and-turn or one-leg stand
Blood test results showing THC or its metabolite
Drug recognition expert (DRE) evaluations if one was called in
Here’s the problem: field sobriety tests were developed and validated for alcohol, not THC. Research shows they’re unreliable for detecting cannabis impairment — yet officers often lean heavily on these results.
As a marijuana DUI defense attorney in Pima County, I’ve cross-examined officers on their lack of training when it comes to THC impairment, their misunderstanding of how marijuana affects the body, and their overreliance on DRE conclusions that can be highly subjective.
Penalties for Marijuana DUIs in Arizona
Another misconception I hear all the time is that a marijuana DUI isn’t “as bad” as an alcohol DUI.
Unfortunately, that’s not true.
If you’re convicted of a first-time marijuana DUI under A.R.S. § 28-1381(A)(1), the penalties are nearly identical to a regular DUI. You’re looking at:
A minimum of 10 days in jail (though 9 can often be suspended)
Fines and fees totaling over $1,500
Substance abuse screening and education
A 90-day driver’s license suspension
Possible SR-22 high-risk insurance
Possible Probation and community service
Here’s one key difference: you are not eligible for an ignition interlock device (IID) in a marijuana-only DUI. That may sound like a good thing — but it’s not. With an alcohol DUI, an interlock is often a way to shorten your license suspension and get you back on the road sooner. Otherwise, you’re stuck with the full 90-day or 1-year license consequences.
The MVD (Motor Vehicle Division) consequences operate separately from the criminal court system. Even if your criminal case is reduced or dismissed, your license can still be suspended if you don’t act quickly to request a hearing or comply with the Admin Per Se process.
Defending Marijuana DUI Charges in Pima County
I’ve been practicing criminal defense in Tucson and throughout Pima County for years, and marijuana DUIs are one of my focus areas. These cases are defensible — and I’ve had dismissals, not guilty verdicts, and many cases resolved with non-DUI outcomes like reckless driving.
Here’s what I look for in building a strong marijuana DUI defense:
Was the stop legal? If the officer didn’t have a valid reason to pull you over, the case could be thrown out entirely.
Were the field sobriety tests valid? If they weren’t administered correctly — or the officer relied on alcohol-based cues to judge marijuana impairment — that’s a big issue.
Was a drug recognition expert involved? And if so, did they actually follow the full 12-step DRE protocol, or just check a few boxes?
What do the lab results really show? I work with forensic toxicologists to challenge the interpretation of THC levels, explain the difference between active THC and inactive metabolites, and point out the lack of scientific consensus about what constitutes impairment.
Are there alternative explanations? Medical conditions, anxiety, sleep deprivation, or even poor balance can mimic signs of impairment. If the officer jumped to conclusions, I’ll make that clear.
In many cases, I’m able to negotiate a favorable outcome early in the case — which saves clients time, money, and stress. In others, we fight all the way to trial. I’m proud of the work I’ve done getting marijuana DUI charges reduced or dismissed for my clients.
What to Do If You’ve Been Charged with a Marijuana DUI in Arizona
If you’re reading this because you or someone you love was recently arrested for a marijuana DUI, don’t panic — but do act quickly.
Your first court date will come fast, and your license could be at risk even before you step foot in front of a judge. The best thing you can do is talk to an experienced marijuana DUI attorney who understands both the law and the science behind these charges.
At AJB Law Firm, I represent clients throughout Tucson and Pima County in marijuana DUI cases. I take a thorough, strategic approach to every case — and I’ve built a strong record of results for people just like you.
Ready to Talk?
You don’t have to go through this alone. If you’ve been charged with a marijuana DUI in Pima County or Southern Arizona, schedule a confidential consultation today. I’ll walk you through your options, explain what to expect, and start building your defense from day one.
Your future is worth fighting for — and I’m here to help.
