Many people assume a DUI charge only applies to alcohol. In reality, Arizona has one of the strictest impaired-driving laws in the United States, and it does not limit DUI offenses to alcohol consumption. A driver can be arrested and charged with DUI even if they have not had a single drink. The law focuses on impairment, and impairment can come from many different sources, including prescription medications, illegal drugs, and even certain over-the-counter substances.
Understanding how non-alcohol DUIs work in Arizona can help drivers avoid unintentional violations and recognize the legal risks associated with driving under the influence of substances other than alcohol.
Arizona’s DUI laws center around two key concepts: whether a substance is present in the body, and whether it affects the ability to drive safely. A person can be charged if they are impaired “to the slightest degree,” a phrase that gives officers broad authority in determining whether someone is driving while affected by drugs, medication, or other substances. This means drivers do not need to be visibly intoxicated or incapable of driving; even subtle indicators of impairment may lead to an arrest.
Because the law does not specify alcohol as the only source of impairment, it applies equally to legal medications, cannabis, controlled substances, and even unfamiliar combinations of drugs that cause drowsiness or cognitive changes.
Many Arizona drivers are surprised to learn they can face DUI accusations while taking medication exactly as prescribed. Drugs used to treat anxiety, pain, sleep disorders, allergies, or ADHD can sometimes cause side effects such as dizziness, delayed response time, blurred vision, or reduced coordination. Even if the medication is fully legal and taken properly, a driver may still be considered impaired if the substance affects their ability to operate a vehicle safely.
Doctors and pharmacists often warn patients about potential impairment, but the responsibility ultimately falls on the driver. The fact that a medication was legally obtained or medically necessary does not shield someone from a potential DUI.
Arizona enforces a strict approach to illegal drugs in the bloodstream. If a substance like methamphetamine, cocaine, heroin, or certain narcotics is detected in a driver’s system, a DUI charge can occur even if the driver does not appear outwardly impaired. This is due to statutes that make it unlawful to drive with certain drugs or their active metabolites present at all. The mere presence of the drug may be enough to trigger a criminal charge, regardless of driving behavior.
This zero-tolerance structure means that time, metabolism, and residual traces can all become factors in a case, even if the driver consumed the substance long before getting behind the wheel.
Arizona’s legalization of medical and recreational marijuana added additional layers to DUI enforcement. Although adults can legally consume cannabis, they cannot drive if they are impaired by it. THC can remain detectable long after the impairing effects have faded, which creates challenges for determining whether someone is actively under the influence.
Unlike alcohol, where specific numbers are used to determine impairment, cannabis does not have a universally accepted measurement that accurately reflects a person’s level of intoxication. Officers rely more heavily on driving behavior, field observations, and the results of a drug recognition evaluation. This makes cannabis-related DUIs unique and often more complex than alcohol-based cases.
When officers suspect impairment unrelated to alcohol, they often use additional tools to assess the driver. Standard field sobriety tests may still be used, but because they were originally developed for alcohol detection, their effectiveness with drugs is limited. In cases where officers believe drugs are involved, a specially trained Drug Recognition Expert (DRE) may be called to evaluate the driver.
These evaluations examine physical signs such as pupil size, muscle tone, vital signs, behavior, and the driver’s ability to follow instructions. None of these tests involves breath alcohol measurement, since no alcohol is suspected. Instead, officers look for physiological indicators that point toward drug impairment.
Unlike alcohol DUIs, which frequently rely on breath tests, drug-based DUI investigations typically involve blood or urine samples. These tests help determine whether a drug or its metabolites are present. Because many substances affect people differently depending on tolerance, dosage, body weight, and metabolism, the presence of a drug alone does not always indicate impairment. However, Arizona law sometimes treats presence as enough for charges, depending on the type of substance involved.
Laboratory results can take days or weeks, meaning the arrest may occur long before toxicology reports are finalized.
There are rare situations in which drivers appear impaired without having consumed drugs or alcohol at all. Medical conditions, sleep deprivation, extreme emotional distress, and neurological episodes can sometimes mimic signs of impairment. Officers are trained to look for these possibilities, but misinterpretations can still occur. Understanding how impairment is evaluated helps drivers recognize how these situations may be viewed by law enforcement.
Many Arizona drivers are familiar with the dangers and consequences of drinking and driving, but far fewer understand the risks connected to medication, cannabis, and other substances that influence the ability to drive. Because Arizona law imposes some of the strictest impairment standards in the nation, even small amounts of certain drugs or minor side effects can lead to serious legal trouble.
Drivers who rely on daily medication, individuals who occasionally use cannabis, and anyone managing chronic pain or anxiety should be aware of how these substances may affect their ability to operate a vehicle safely. Understanding these laws improves public safety and helps prevent unintentional violations that may result in criminal charges.
