DUI – Drugs

Driving under the influence of drugs (DUID) is the operation of a motor vehicle while under the influence of or impaired by any type of drug, legal or illegal. This includes marijuana, prescription drugs, and some over-the-counter medications.

While research estimating the crash risk of driving under the influence of drugs is ongoing, many experimental studies have shown that drugs impair attention, alertness, reaction time, lane tracking, coordination, and perception of time and distance.  Even small amounts of some drugs can have a serious effect on driving ability.

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Nationally, drug-related traffic crashes now surpass alcohol-related crashes. In 2016, among drivers tested in fatal crashes, 44% had used a legal or illegal drug, compared with 38% who tested positive for alcohol.

Even if medications are legal and prescribed or recommended by a clinician, some can impair cognition and motor skills necessary for safe driving. Substances include marijuana, prescription drugs, and over-the-counter medications such as cough suppressants, antihistamines, and sleep aids.

In 2013–2014, the National Highway Traffic Safety Administration’s National Roadside Survey of Alcohol and Drug Use by Drivers found drugs in 20% of all drivers on weekend nights.



Marijuana use is increasing nationally. According to a 2014 survey conducted by the CDC, there were 7,000 new marijuana users per day. This increase may be due to the changing legal landscape regarding marijuana use. The increase in drug-related driving deaths coincided with marijuana legalization in some states.

After alcohol, marijuana is the most common drug found in drivers killed in drug-related crashes. In 2016, of the 44% of drivers killed in crashes who tested positive for drugs, 41% had used some form of marijuana.



An especially dangerous upward trend in the misuse of prescription drugs has become known as the “U.S. opioid epidemic.”  Prescription opioids are potent pain medications that can affect driving by causing drowsiness and impairing cognitive function. Prescriptions for drugs such as oxycodone (OxyContin), hydrocodone (Vicodin), and morphine have quadrupled from 76 million in 1991 to nearly 300 million in 2014. In 2016, 19% of drivers killed in crashes who tested positive for drugs tested positive for some opioid.


For more information, visit the Resources tab.

In 2016, California voters approved Proposition 64, the Medicinal and Adult-Use Cannabis Regulation and Safety Act. This law allows adults 21 and over to purchase, possess, and consume up to 28.5 grams of marijuana in their private residence or in an establishment licensed for marijuana consumption.

To buy medicinal cannabis, you must be 18 or older and have either a current physician’s recommendation, a valid county-issued medical marijuana identification card, or be a Primary Caregiver as defined in Health and Safety Code Section 11362.7(d).

In California, the same statute that makes alcohol-impaired driving illegal also covers drug-impaired driving. This law makes it unlawful to drive while:

  • under the influence of any drug, or
  • under the combined influence of alcohol and drugs

Driving under the influence of alcohol or drugs has the same legal and financial consequences:

  • Up to $15,000 in fines, penalties, and fees for a first conviction
  • License suspension
  • Criminal record
  • Jail time if there are injuries

The California Department of Public Health has information on their “Let’s Talk Cannabis” website regarding what is legal for adult use in California.


Overview of NHTSA’s Current Drugged Driving Research. This report summarizes data sources for research on drug-impaired driving, such as the National Survey on Drug Use and Health (Substance Abuse and Mental Health Services Administration), Monitoring the Future (University of Michigan-NIDA), and the National Roadside Survey (National Highway Traffic Safety Administration), among others.

Trends in Prescription Opioids Detected in Fatally Injured Drivers in 6 US States: 1995-2015.  The prevalence of prescription opioids detected in fatally injured drivers has increased in the past two decades. The need to assess the effect of increased prescription opioid use on traffic safety is urgent.

Drug-Impaired Driving: Marijuana and Opioids Raise Critical Issues for States. This report from the Governors Highway Safety Association provides key facts about drug-impaired driving to help readers understand the impact of marijuana and opioids on driving safety.

Driving High is DUI. Developed by TREDS, this fact card for the public addresses THC potency, the ‘high’ resulting from edibles compared to inhaling, and legal consequences resulting from a cannabis DUI conviction, whether consumed for medical or recreational purposes. To request a camera-ready pdf for reprinting, contact us at TREDS.


English PDF   |   Spanish PDF

Drug-Impaired Driving. This report from the National Highway Traffic Safety Administration provides an overview on issues related to drug-impaired driving and includes a list of resources from NHTSA.

Drug-Impaired Driving Call to Action. On March 15, 2018 the U.S. Department of Transportation’s National Highway Traffic Safety Administration launched its drug-impaired driving initiative. It brought together key stakeholders, including safety partners, data and policy experts, law enforcement and criminal justice professionals, toxicologists and drug recognition experts to start a national dialogue on how to combat drug-impaired driving.

Drugged Driving (2016). This publication is part of NIDA’s Drug Facts series and provides a concise overview of issues related to drug-impaired driving.

Drugged Driving Resources. This project from Innovation Research and Training, Inc., aims to prevent and reduce the problem of drug-impaired driving in communities through the dissemination of research-informed and evidence-based resources.

Impaired Driving: Marijuana and Driving. This website from Ventura County Behavioral Health includes a range of resources and tools on drug-impaired driving information and prevention. This effort to support personal and public safety aims to reduce DUIs due to marijuana, prescription and over-the-counter drugs.

Let’s Talk Cannabis.  The California Department of Health is committed to providing the public with facts needed to make safe and informed choices. This webpage includes science-based information to increase awareness about cannabis and its effects on the body, mind, and health.

Stop DUID.  This program’s goal is to provide the most recent information on policies and technologies aimed at reducing drug-impaired driving in the United States. The website tracks research and legislative activity to strengthen DUID laws in all 50 states and includes information on what police, politicians, prosecutors, and others are doing to confront this growing epidemic.

What You Need to Know About Marijuana Use and Driving. This fact sheet from the Centers for Disease Control and Prevention (CDC) describes the risks associated with marijuana use and driving.

In an effort to reduce impaired driving on California’s roadways, four short videos were created to raise awareness that driving under the influence of cannabis can result in a DUI.  Help to save lives by sharing these videos on your social media sites.

TREDS offers a free program for adults on worksites and organization to promote social responsibility and roadway safety.  Higher Education is a 60-minute interactive class that discusses the impact of cannabis and prescription medication on driving. The program is delivered by law enforcement and public health professionals.

Topics addressed in the class:

  • Scope of the problem
  • Effects of cannabis and prescription drugs on driving
  • Standardized Field Sobriety Testing
  • Personal, legal, and financial consequences of DUI
  • Strategies to promote safe driving

Contact us for additional information or to request training.