DUI & Criminal Defense

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Arizona Drug DUI (Updated 2019)

DUI drugs cases, often referred to by police as “drugged” driving, have received much more attention in the past few years. As your family members, friends and neighbors take more prescription medications; and the rate of addiction to illegal drugs rises, so does the prosecution of DUI drug cases.

Arizona Drug DUI Laws Fail to Consider…

According to a recent study by the Mayo Clinic 70% of Americans are taking prescription drugs. The study also finds that 20% percent of patients are taking five (5) or more prescription medications (maybe you should ask Grandma). How any medication effects you, the duration of its effects, and the severity of any side effects is person specific.   Not everyone responds exactly the same to a drug, at the same dose.

With these numbers in mind, pick any magazine (if magazines are still a thing by the time you read this). You will find an advertisement for a drug being sold at your pharmacy. Look at the back page of the advertisement. There are dozens of potential side effects listed.

Many of the listed side effects can be argued as a sign of impairment by law enforcement. This is true even when the medication is taken every day to reduce your cholesterol. For the person taking a sleep aid such as Ambien, there is a real danger.  The Ambien will still be in your system (and no longer impairing) but the “jitters” observed by a police officer the next day during a traffic stop were caused by your Lipitor. Drug impairment, in Arizona DUI Drug cases, is apparently in the eye of the beholder.

Drug DUI Prosecution Overreach

No reasonable person advocates for the legality of driving while impaired by a drug or medication. Unfortunately, the real issue is the overreach by law enforcement in Arizona drug DUI cases claiming they can systematically detect impairment from a medication or a drug. These cases are usually prosecuted without any legitimate scientific evidence of impairment. The “I know it when I see diagnoses” of impairment has been covered in a cloak of pseudo-science that the would never be accepted by the scientific community outside of “forensics”.


These cases stand directly at the crossroads of where science and law meet. On their face, it would be easy to jump to the conclusion that Arizona Drug DUI cases are the same thing as an alcohol DUI. While the statutes making the underlying conduct illegal appear similar, evaluating the evidence requires a sound understanding of the basic toxicology of the drug(s) at issue.  Once you have this background, you learn the fundamental difference between a DUI based upon alcohol and one based upon drugs.  Unlike an alcohol case, in an Arizona drug DUI, a chemical test cannot tell you anything about whether a person is impaired.

The Science of Drug DUI

It is well settled in the scientific community that a chemical test cannot determine impairment.  Even the National Highway Safety Traffic Administration’s training manual provides: “Interpretation of Blood Concentrations: It is difficult to establish a relationship between a person’s the blood or plasma concentration and performance impairing effects.” NHTSA Drugs and Human Performance Fact Sheet, page 8.  In a case of a urine sample, the manual also recognizes: “Interpretation of Urine Test Results: Detection of total THC metabolites in urine, primarily THC-COOH-glucuronide, only indicates prior THC exposure. The “[d]etection time is well past the window of intoxication and impairment.” NHTSA Drugs and Human Performance Fact Sheet, page 9.

In addition, while the law may treat an Arizona drug DUI similar to an alcohol DUI, the public certainly feels differently about them. Based upon my experience over the last 20 years with these cases (as both a prosecutor and defense attorney) the public often looks at drugged driving allegations much more skeptically than alcohol cases. This is particularly true for allegations where the police claim you are impaired by prescription medication and/or marijuana.


Legally, as with alcohol, these cases usually consist of both an “impaired” driving count and a type of per se violation. A typical drug DUI case will start with you receiving two charges alleging that you were driving:

  • While impaired by a drug while driving [A.R.S 28-1381(a)(1)]; and
  • While having an illegal drug or its metabolite in your body [A.R.S 28-1381(a)(3)]

If convicted, the legally required penalties for either count is substantially the same those of an alcohol-based conviction. The primary difference is that a drug DUI conviction can result in more serve consequence for your driver’s license (i.e. 1-year license revocation).


As with alcohol cases, Arizona law makes it illegal to drive while impaired by a drug.  Also similar to an alcohol DUI, our legislature has made a companion charge to the driving while impaired by a drug violation.  This charge is called a per se violation.  Per se meaning  “by itself.”  This part of the law makes it illegal to drive while having a drug (or its metabolite) is in your system regardless of whether it is impairing while driving.

If you have ever had outpatient surgery, there is a good chance that you received a pain medication such a Vicodin, Percocet or Oxycodone. All of the medications have psychoactive (mind-altering) effects. Thus, it would be unwise to attempt most of your daily activities while taking them. In addition to being unwise, it is also illegal to drive your car while being impaired by any of them. This is true despite the fact you have a legal prescription to consume the medication. The prescription does not give you permission to operate a vehicle while under impaired by the medication. Obviously, the same logic and law apply to any illegal drug.

The defense to the per se drug DUI charge is having a valid prescription – not that the medication at issue is capable of being prescribed.  For example, your spouse may have a prescription muscle relaxer they were prescribed several months ago in your medicine cabinet.  If you injure your back one day and use this medication, this act in and of itself is illegal.  In addition, driving while this medication is in your system is also considered a DUI in Arizona.

When you go to your doctor because of nagging pain in your lower neck, it is safe to say that you will not leave with a prescription for methamphetamine. Some drugs are not able to be legally prescribed in Arizona. These commonly called “street drugs.” A few examples of these drugs include:

Driving while any illegal street drug in your system is considered a drug DUI under Arizona law.


Most Drug DUI cases involve a blood sample being tested by a machine called a gas chromatograph. Alcohol cases use a technique called headspace gas chromatography. In Arizona Drug DUI police different forms of mass spectrometry to test urine or blood samples for the presence of a drug.

Arizona Does Not Regulate Forensic Drug Testing

The are currently no regulations governing the analysis of urine or blood.  Unlike alcohol, there is no permit required by the State to perform a drug quantification test.  One consequence of this lack of regulations is differing “cut-off” levels for the identification of drugs in a blood sample.  Thus, a person with a blood test showing 3 nanograms of THC could have a much different fate depending on the lab doing the testing.  


Arizona Drug DUI laws prohibit driving while there is an illegal drug in your body, and also, “its metabolite.” Thus, it is important to understand what is and is not “its metabolite.”

Your metabolism clears drugs from your body. Through your metabolic system, a drug is converted into different chemicals. These new chemicals are called metabolites. A drug can be metabolized into a new type of drug. Some metabolites can be active in the body. That is, there are some metabolites capable of causing impairment…and many that are not.


As stated above, a chemical test cannot tell you if a person is impaired by a drug.  It is simply beyond the abilities of chemistry.   Thus, this reality presents law enforcement with a problem in the prosecution of Arizona Drug DUI cases.  As a result, they developed their own impairment recognition program.  Law enforcement “Drug Recognition Program” has been the subject of widespread criticism by scientists, scholars, and courts as lacking scientific validity.  That is, their “evaluation” does not actually measure what it claims to measure.


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