Drugged Driving: A Pressing Road Danger that Demands Immediate Attention

April 27, 2026

Andrew Yockey, PhD, Author and Assistant Professor of Public Health, University of Mississippi

Tim Lineaweaver, Subject Matter Expert

In October 2023, a tragic event occurred in Coleman, Wisconsin: an 8-month-old girl lost her life when a driver impaired by cannabis ran a stop sign and collided with another vehicle. In February 2025, the driver pleaded guilty to negligent vehicular homicide and drugged driving with a minor passenger, and now faces up to 10 years in prison.

These tragic yet preventable events underscore a harsh reality: drugged driving, like alcohol-impaired driving, can be deadly. The increasing prevalence of drug-impaired driving across the United States is a cause for concern.

However, our efforts in public awareness and policy responses are not keeping pace with the growing problem of drugged driving. There's an urgent need for more effective strategies.

I research the prevalence and risk factors of drugged driving. While public health messaging in the U.S. has long focused on the dangers of alcohol-impaired driving, much less attention has been given to the risks posed by other substances — even as drug-impaired driving grows more widespread and complex.

Whether the substance is illegal, such as methamphetamine, or legal but still impairing, like cannabis, sedating sleep aids, or certain prescription drugs like benzodiazepines and painkillers, the outcome remains the same: impaired judgment, slowed reflexes, and devastating consequences on the road.

A Different Form of Impairment: Drugged Driving

In 2020, an estimated 12.6 million people aged 16 and older drove after using illicit drugs. Of those, roughly 11.7 million were under the influence of cannabis. In 2018, about 2.3 million people in the United States reported driving under the influence of illicit drugs other than marijuana during the previous 12 months. Globally, roadside surveys worldwide find that between 3.9% and 20% of drivers tested positive for drugs.

While alcohol generally impairs coordination and reaction time, drugs create a more complex picture. Cannabis, for example, slows reaction time and affects spatial awareness. Opioids can cause drowsiness and dizziness. Stimulants like cocaine or methamphetamine may lead to overconfidence and aggressive driving. When drugs are mixed—or combined with alcohol—the risks increase significantly.

Cannabis, in particular, presents a unique challenge: it is the most commonly used federally illegal drug in the United States, and public perception often underestimates its risks behind the wheel.

Research from the AAA Foundation for Traffic Safety shows that over 80% of cannabis users admit to driving just hours after using the drug, and nearly 20% believe their driving has improved. Multiple studies have found that drivers with THC, the primary psychoactive compound in cannabis, in their bloodstream are about twice as likely to be involved in a fatal crash—either as the cause or as a victim—compared with those who haven't used drugs or alcohol. For alcohol, with a blood alcohol content of 0.08%, the odds of dying in a motor vehicle crash are approximately 13 times higher than for sober drivers.

Outdated Laws and Inconsistent Enforcement

Every U.S. state has laws prohibiting drug-impaired driving, but enforcement varies greatly. Some states, such as Texas and California, employ "impairment-based" laws that rely on observable signs of impairment. Others, such as Ohio and Wisconsin, use per se laws, which set specific thresholds for drugs like THC, such as five nanograms per milliliter of blood. 

Then there are zero-tolerance laws, found in states like Georgia and Rhode Island, which punish drivers for having any trace of a controlled substance while behind the wheel, regardless of impairment at the time. 

These differences lead to legal gray areas in how laws are interpreted and enforced. For example, in Illinois, it's a crime to drive with any trace of a controlled substance in your system—even if you're not impaired—and even if the drug was legally prescribed. In Arizona, medical cannabis patients cannot be convicted solely based on THC presence, but prosecutors can still argue impairment. Detection remains the biggest challenge.

Detection is the Biggest Hurdle.

A significant factor in the inconsistency from state to state is that there is no standardized way to measure drug impairment, as there is with blood alcohol content.

While alcohol can be tested on the spot using a breathalyzer, detecting drug use is far more complicated. THC and other substances can linger in the body long after their impairing effects have worn off. Meanwhile, newer synthetic drugs such as spice or bath salts may not be detected at all without specialized equipment.

To address this, many states are turning to oral fluid testing — or saliva tests — which can detect recent drug use more quickly. As of late 2023, 27 states had authorized some form of roadside oral fluid screening.

Public Misconceptions and Potential Solutions

Unlike alcohol, where there's a clear legal limit of 0.08% blood alcohol concentration, there's no easy-to-understand number for cannabis. Laws around driving after cannabis use vary widely and can be confusing. Scientists are still figuring out how much THC it takes to affect a person's driving skills and to what degree, so it stands to reason that people don't know how to judge it for themselves.

Another twist is that the roadside tests that cops use to spot drunk drivers don't work as well for drug impairment. THC can linger in the body long after the high fades, so a test might not tell the whole story. New testing tools, such as saliva swabs and eye-tracking, are being developed but are not yet ready for application in real-life scenarios.

So what can you do? The big takeaway is that if you feel "different," you're probably driving differently, too. The National Highway Traffic Safety Administration's "If You Feel Different, You Drive Different" campaign is a helpful reminder that even if you think you're fine, your driving might not be.

If you're riding with friends, don't be shy about speaking up if someone looks or behaves as if they are impaired. Planning with a designated driver or using a ride-share service can make all the difference.

At the end of the day, it's about making intelligent, safer choices – and being honest with ourselves and each other about what it really means to be safe on the road.

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Dr. Andrew Yockey examines and applies unique statistical methods and survey procedures to study substance use prevention and child/adolescent health risk behaviors. He also utilizes meta-analytic, longitudinal, and multi-level techniques to enhance statistical modeling and functional analysis.

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