W. Michael Walz, P.C. - Pot Lawyer - Phoenix, AZ
W. Michael Walz, P.C. - Pot Lawyer - Phoenix, AZ

W. Michael Walz, P.C. - Pot Lawyer - Phoenix, AZ

W. Michael Walz, P.C. - Pot Lawyer - Phoenix, AZ

Below, Mr. Walz's long held position on Marijuana DUI including research and consulting with other firms, has been verified by an Arizona Appellate Court. See State ex rel. Montgomery v. Harris, 234 Ariz. 343, 322 P.3d 160, (2014) or view here: Court Case | Decision Reversed

Marijuana DUI

Knowledge of the biochemistry of tetrahydrocannabinol (THC) and its metabolism by the liver and other organs is essential to understand the defense to these charges. Many lawyers have no clue -- even though they advertise for DUI. Alcohol DUIs and marijuana DUIs are not the same.

Hydroxy vs. Carboxy

Why it matters? If your blood or urine result comes back positive for carboxy tetrahydrocannabinol this merely indicates that you have ingested marijuana within the past several weeks. Carboxy THC cannot cause impairment no matter how elevated the level.

However if your test result reveals a level of hydroxy tetrahydrocannabinol, you may be impaired and should consider pleading guilty (unless there is some other defense). Impairment does not matter under the A(3) charge {see below}; the law forbids anyone driving to have hydroxy THC or THC in their body.


People arrested for DUI (drugs) for using marijuana are usually charged with 2 separate offenses. ARS 28-1381 A(1) and ARS 28-1381 A(3).

The A(1) charge is that you were impaired by marijuana so that it affected your ability to drive.

The A(3) charge is that 'there was an illegal drug or its metabolite in your body at the time of driving.'


A(1) no physical signs; the person acted straight; the tests were designed for alcohol DUI; person knows and testifies truthfully; no dangerous driving.

A(3) there was no tetrahydrocannabinol nor any hydroxy tetrahydrocannabinol, were found in the person's body.


Potsmokers know that smoking the night before does not make you impaired to drive the next day. Yet many people, often with the advice of a lawyer, plead guilty to DUI based upon a test of their urine or blood. It is essential that the test result be positive for 'a drug defined by ARS 13-3401 or its metabolite' (emphasis added). Therefore your lawyer must know the drugs defined by ARS 3401 and the metabolic sequence of the drugs.

The State takes the position that any and all metabolites are illegal to have in your body at the time of driving.

Ultimately, the Judge or jury may decide the issue and the outcome probably depend on the facts of your case. Hiring a lawyer who understands the issues and the underlying science greatly increases your chances for success.

Licensed Medical Marijuana Patients

Registered patients licensed under the Arizona Medical Marijuana Act (AMMA) are provided special protection from a marijuana DUI conviction. They may still be convicted of a DUI if the jury finds that the patient was impaired by marijuana. However, recently the Arizona Supreme Court determined that if the medical marijuana patient can prove that they did not have an impairing level of THC in their body, that they are not guilty of the A(3) charge of DUI. Dobson v. McClennen Arizona Supreme Court Decision, filed Nov. 20, 2015 View Court Case

Pot Lawyer W. Michael Walz - Criminal Defense of Marijuana Cases.