There Is No "Standard" DUI Defense
Every Arizona DUI case turns on a handful of decisions made in the first 48 hours: whether the stop was lawful, whether the field sobriety tests were administered to NHTSA standards, whether the breath or blood sample was collected and preserved correctly, and whether the State can actually prove impairment at the time of driving — not just at the time of testing. A real defense attacks each of these links in the chain, one at a time.
Attacking the Stop
An officer needs reasonable suspicion of a traffic violation or criminal activity to pull you over. If the stop was based on a vague hunch, an anonymous tip that wasn't corroborated, or a "driving cue" that doesn't actually appear in the NHTSA 24-cue list, a motion to suppress can end the case before trial. We request every piece of dash-cam and body-cam footage and compare it frame-by-frame to the officer's written report.
Attacking the Field Sobriety Tests
The Horizontal Gaze Nystagmus, Walk-and-Turn, and One-Leg Stand are the only three SFSTs NHTSA has validated — and they were only validated under specific conditions. Uneven pavement, poor lighting, footwear, medical conditions, age, and weight all degrade accuracy. We cross-reference the officer's administration against the NHTSA manual (available free in our NHTSA Manuals library) to find every deviation.
Attacking the Chemical Test
Arizona breath tests are almost always run on the Intoxilyzer 8000. The machine requires a 20-minute deprivation period, a valid calibration check within the last 31 days, and a qualified operator. Blood draws require a valid medical technician, an approved collection kit, and an unbroken chain of custody. Any one of these failures can exclude the result entirely.
Attacking a Marijuana DUI
Marijuana DUI works very differently from alcohol DUI in Arizona, and the State carries a heavier burden. There is no per-se concentration of THC that makes you guilty by the numbers — Prop 207 / A.R.S. § 36-2852(B) and Dobson v. McClennen, 236 Ariz. 408 (2015), require the State to prove actual impairment for adults 21+, and State ex rel. Montgomery v. Harris, 234 Ariz. 343 (2014), excluded the non-impairing Carboxy-THC metabolite from the A.R.S. § 28-1381(A)(3) "drug or its metabolite" theory. Practically, that pushes most marijuana cases to A.R.S. § 28-1381(A)(1) — "impaired to the slightest degree" — which the State must prove with conduct evidence, not a number on a lab report.
That conduct evidence is where these cases fall apart. NHTSA has never validated any standardized field sobriety test for marijuana impairment. The HGN, Walk-and-Turn, and One-Leg Stand were developed and validated only for alcohol. Officers and Drug Recognition Experts (DREs) often present them at trial as if they prove cannabis impairment; they don't. Combined with the lag between consumption and a blood draw — and the wide range of "normal" THC and Hydroxy-THC concentrations across users — the State frequently cannot prove impairment beyond a reasonable doubt. A motion in limine to exclude the SFST results as junk science for cannabis, paired with a cross of the DRE's twelve-step protocol against peer-reviewed literature, is often the case-winning move.
Attacking the "Within Two Hours" Element on an Alcohol Case
For alcohol cases under A.R.S. § 28-1381(A)(2), the State must prove a BAC of 0.08 or more within two hours of driving. If the breath or blood test was taken outside that window, the State has to fall back on retrograde extrapolation — a scientific fight that turns on absorption rate, last drink time, food in the stomach, and the assumptions in the State's expert's model. We routinely defeat extrapolation evidence on cross.
Negotiating From a Position of Strength
Every defense we build creates leverage. A strong suppression motion filed early often produces a plea to a lesser charge — reckless driving, endangerment, or a straight reduction to a lower BAC tier. The goal is always the best outcome for the client, and that outcome depends entirely on the quality of the pre-trial work.