Arizona has strict laws about driving while drugs, illegal or prescription, or their impairing metabolites are in your system. There are actually two ways that the State of Arizona attempts to prosecute these types of cases: (1) by alleging that the drug is impairing the driver to the slightest degree; (2) based on the driver having any measurable amount of a listed drug (referred to in A.R.S. §13-3401) or its impairing metabolite in his or her blood.

Discrepancies: Science -vs- Legal Enforcement

It seems daunting to fight a criminal charge with such low standards, but it’s important to know, however, the science behind prosecution of DUI drug cases is very suspect. In fact, the overwhelming majority of scientific literature is critical and does not support methods and conclusions that are often embraced by prosecutors and police officers alike. DUI drug cases need to be examined on a case by case basis. In many circumstances, the scientific literature and research may demonstrate that a drug’s presence in the blood stream has no negative impact on a person’s driving, such as when taken at the prescribed or “therapeutic” dose.

So let’s examine DUI-marijuana cases. While many states have passed legislation authorizing the recreational use of marijuana, it is only legal here in Arizona for medical purposes. Be aware, however, that having a medical marijuana card or endorsement does not protect a person from DUI charges if he or she has THC or its active metabolite in his or system while driving; that person can still be charged if there is an allegation that the THC is impairing the person’s ability to drive.

No "Legal Limit" in Arizona

Notably, in Arizona, there is no “legal limit” for marijuana like the 5ng/mL THC legal limit in Colorado. Despite many recent studies, doctors and scientists in the field have not yet been able to establish a specific level of THC in the bloodstream that will impair all persons for the task of driving. On the other hand, all experts will say that, given a complex enough driving situation, everyone is impaired by alcohol at a .08 BAC.

While there has been a lot of research exploring the effects of alcohol on the human body, leading scientists to agree that every person will be impaired to drive a vehicle with a BAC of .08, this is not the case for marijuana, thus leading many State experts to acknowledge that the amount reported from their examination may or may not be impairing.

What is the Standard?

So what is illegal in Arizona regarding driving and marijuana? There are two ways to be arrested and charged with DUI-marijuana: either to have a measurable amount of THC or its impairing metabolite (the active portions of marijuana) in your system while driving, or if the marijuana used impairs you to the slightest degree while driving. Luckily, if there are traces of the THC that are now inactive and thus non-impairing, they are not grounds for a DUI-marijuana. State v. Harris (Shilgevorkyan), 237 Ariz. 98 (2014).

Another critical aspect of DUI-marijuana defense that uses universally agreed upon science to limit or preclude DUI-marijuana prosecution is the fact that simply because the active, impairing compound in marijuana, THC, in the bloodstream is far from valid, scientific evidence to support a DUI-Marijuana conviction on impairment grounds. Ishak v. McClennen, 241 Ariz. 364 (App. 2016), determined that unlike alcohol, there is no universal level of impairment for marijuana. The main reason for this, which will also be touched upon later in DUI-Prescription Drugs, is that there is inadequate research on the subject and, most importantly, on the issue of tolerance.  

What is Enforced? 

Finally, it makes no difference whether a lawful, medical marijuana cardholder is using the dried buds or consuming in the form of edibles or other extracts as it relates to DUI or possession charges. Although the Arizona criminal statutes classify the two as different substances (the dried plant as marijuana, the extract or resin as a narcotic drug), the Arizona Supreme Court recently confirmed that AMMA, the Arizona Medical Marijuana Act, defined marijuana as the plant or any derivation of the plant. State v. Jones, CR-18-0370-PR (Ariz. 2019).

As long as someone has a valid medical marijuana card or endorsement and possesses no more than the maximum quantity, he or she will be governed by the AMMA statutes and definitions, not the criminal statutes for possession purposes.

Experienced Legal Representation is Essential

Having successfully defended many clients facing DUI-marijuana charges, this office knows that it is imperative that your attorney understand the case law and the science behind how marijuana affects the human body, how officers can or cannot support their observations regarding impairment, and the testing process used by the state’s scientists.

The DUI attorney needs to be familiar with the studies regarding marijuana and driving, the conflicting opinions regarding impairment, and the testing process used by the State’s scientists. Most importantly, your attorney should be looking at your case on an individualized basis to address factual, legal, and scientific issues, and help you uphold your rights and defend your case.