Impaired Driving

AAA Survey: Users of Marijuana and Alcohol Take More Risks Behind the Wheel

As 4/20 looms, AAA Survey Finds Users of Both Admit Variety of Dangerous Driving Behaviors


With 4/20 rapidly approaching, AAA is issuing a warning about the dangers of driving impaired. New AAA research suggests that users of both alcohol and marijuana (not necessarily at the same time) are often some of the most dangerous drivers on the road. According to the research, drivers who consumed marijuana and alcohol within a 30 day period were more likely to engage in risky behavior like speeding, texting, intentionally running red lights, and aggressive driving.

“Regardless of whether marijuana is legal or prescribed, driving under the influence of the drug is illegal and extremely dangerous,” said Mark Jenkins, spokesman, AAA – The Auto Club Group. “Although some drivers think marijuana makes them a better driver, research shows it can inhibit concentration, slow reaction times, and cloud judgment. That judgement is even more compromised by a marijuana user who also drinks alcohol. It’s important that drivers know the risk that comes with these two drugs and never drive impaired.”

The AAA Foundation for Traffic Safety’s annual Traffic Safety Culture Index found that drivers who use both marijuana and alcohol were significantly more prone to driving under the influence of alcohol (Table 1) versus those who only drink alcohol but do not use marijuana. These motorists identified as someone who consumed alcohol and used marijuana in the past 30 days, and in some cases, they may have used both at the same time. They also engage in various other dangerous driving behaviors far more than drivers who consume either just alcohol or abstain from either drinking alcohol or using marijuana.

Driving Habits of Marijuana and Alcohol Users vs. Users of Alcohol only

Compared to alcohol-only users, drivers who admitted to using both drugs were more likely to report such behaviors as:

  • Speeding on residential streets (55%) vs. alcohol-only (35%)
  • Aggressive driving (52%) vs. alcohol-only (28%)
  • Intentional red-light running (48%) vs alcohol-only (32%)
  • Texting while driving (40%) vs. alcohol-only (21%)

Unsurprisingly, the study found drivers who neither drink alcohol nor use marijuana were considerably less likely to engage in the sorts of risky driving behaviors examined. This Foundation research was published in January 2021 in the peer-reviewed journal Transportation Research Record. (See abstract)

Colorado has a drugged driving problem.

Lukas Myers knows this.  The photo shows him being extracted from a car when he was 12 years old after a crash caused by a marijuana-impaired driver.  Most bones in both of Lukas’s legs were broken as well as both wrists.  

For some, stories like this are convincing.  Others need data.  So here is a summary of relevant data from 10 sources.

  1. Percent of drivers who admit driving after marijuana use:
    • 18.6% of past-30 day adult marijuana users[1]
    • 54.4%% of past-30 day high school student marijuana users[2]
  2. Toxicology tests of those arrested for DUI[3]:
Drug categoryNumber
CannabinoidsPositive screens4,205
 THC positive4,069
Alcohol 3,956
Benzodiazepines 1,774
Methamphetamine and similar 1,090
Cocaine    838
Opioids/opiates    699
Sleeping Zs    115
Barbituates      51

Note: CBI  data from Jul 2019 to Jun 2020 when all DUI blood samples were tested for both alcohol and a full drug panel. 

  1. DUI charges– percent caused by alcohol, THC and polydrug use – 3 year trend [4]
 20162018Percentage change
THC  5.4%  6.4%+18.5%
  1. Traffic deaths per Billion Vehicle Miles Traveled (BVMT):
    • Increased from 9.91 in the five years before marijuana commercialization to 11.26 in the five years after marijuana commercialization[5].
    • Increase of 1.46 deaths/BVMT per year adjusted after marijuana commercialization, compared with a synthetic control[6].
    • Increase of 1.9 deaths/BVMT per year adjusted after marijuana commercialization, compared with states with stable legalization policies[7].
    • Increase of 1.7 deaths/BVMT per year non-adjusted after marijuana commercialization compared with states without legal recreational or medical marijuana[8].

Note: the above reports measured the effect of marijuana commercialization in 2014, not marijuana legalization in 2012.

  1. Traffic fatalities implicating THC:

There were 632 traffic fatalities in 2018.  87% of the drivers in those fatal crashes were tested for drugs.  83 tested positive for THC including 36 at or above 5 ng/ml[9].

  1. Vehicular homicide convictions by drug group in 2016[10]:
Drugs detectedNumber
Alcohol only10
THC only2
Single other drug only1
Alcohol + THC2
Alcohol + other drug1
Alcohol + THC + other drug2

So what is Colorado doing about the problem?

    Deny the problem exists

In 2020 the Department of Motor Vehicles revised the Driver Handbook to say, “…it is unclear whether cannabis use increases the risk of car crashes.”

    Encourage marijuana use

During the COVID pandemic shutdown, marijuana dealers were classified as an “essential business” by the Governor, permitting them to sell their product while non-essential businesses were required to close.

Home delivery of marijuana was authorized, ostensibly to reduce drugged driving.

At the December 14, 2020 meeting of the Retail Marijuana Public Health Advisory Committee, the Colorado Department of Public Health an Environment announced that henceforth, “marijuana users” were to be referred to as “cannabis consumers” since the former label is pejorative.  You just can’t make this stuff up.

    Subsidize the marijuana industry

Governor Polis announced a $584,399 tax credit to Canadian marijuana company SLANG Worldwide to expand operations in Colorado.

On a side note that may not be completely unrelated, Governor Polis is rated A+ by NORML, the National Organization to Reform Marijuana Laws.




[4] Rosenthal A, Reed J. Driving Under the Influence of Drugs and Alcohol.  Colorado Department of Public Safety, Division of Criminal Justice, Office of Research and Statistics, Nov 2020

[5] Federal Highway Administration,

[6] Santaella-Tenorio J, Wheeler-Martin K, DiMaggio CJ et al. Association of Recreational Cannabis Laws in Colorado and Washington State With Changes in Traffic Fatalities, 2005-2017. JAMA Intern Med. Published Online June 22 (2020)

[7] Aydelotte JD, Mardock AL, Mancheski CA et al. Fatal crashes in the 5 years after recreational marijuana legalization in Colorado and Washington. Accident Analysis and Prevention 132 (2019) 105284

[8] Kamer RS, Warshafsky S, Kamaer GC. Change in Traffic Fatality Rates in the First 4 States to Legalize Recreational Marijuana. JAMA Intern Med. Published Online June 22 (2020)

[9] Gorman T. The Legalization of Marijuana in Colorado: The Impact. Vol 6 Sept 2019. Rocky Mountain High Intensity Drug Trafficking Area

[10] Bui B, Reed J. Driving Under the Influence of Alcohol and Drugs. A Report Pursuant to HB 17-1315. July 2018. Colorado Division of Criminal Justice

Stoned driving more common than drunk driving

Posted on 07.17.20 by Ed Wood

Colorado authorized the use of marijuana tax dollars to temporarily fund a program at the Colorado Bureau of Investigation’s Forensic Toxicology laboratory, enabling them to test all DUI toxicology samples for drugs as well as alcohol.  The laboratory issued summary results June 30, 2020 after completing the first year of this program.  CBI performs about half of all the DUI lab tests in the state.

For the last year, stoned driving topped drunk driving, something we’ve never had the data to prove before.  There were 12,771 positive results for drugs and alcohol from the 9,763 sample submissions, an indication of the prevalence of polydrug impairment.

Highlights of the report include:

THC positive cases                   4,069, 51% of which were below 5 ng/ml

Alcohol positive cases              3,956

Benzodiazepines                       1,774, 12.8% of which were designer drugs

Methamphetamine family       1,090

Cocaine                                         838

Opiates/opioids                           699

Recreational pot laws may boost traffic deaths, studies say

New research links laws legalizing recreational marijuana with an increase in traffic deaths

By LINDSEY TANNER AP Medical WriterJune 22, 2020


One study found an excess 75 traffic deaths per year after retail sales began in Colorado in January 2014, compared with states without similar laws. But it found no similar change in Washington state.

The other study looked at those states plus two others that allow recreational pot sales, Oregon and Alaska. If every state legalized recreational marijuana sales, an extra 6,800 people would die each year in traffic accidents, the researchers calculated. They found an increase of 2 deaths per billion miles traveled compared with 20 states without those laws. That change was slightly higher than in the other study.

Fatal Crashes Involving Drivers Who Test Positive for Marijuana Increase After State Legalizes Drug


The latest AAA Foundation research found that between 2008 and 2012 – the five-year period before the drug was legal – an estimated 8.8% of Washington drivers involved in fatal crashes were positive for THC. That rate rose to 18% between 2013 and 2017.

The average number of THC-positive drivers increased, too. 

Recreational Cannabis Impairs Driving Even When driver Not High: Harvard Research

Recreational cannabis use affects driving ability even when drivers are not intoxicated by marijuana, according to a study from a Harvard Medical School hospital.

Published in the Drug and Alcohol Dependence journal, the study “Recreational Cannabis Use Impairs Driving Performance in the Absence of Acute Intoxication,” finds that in addition to chronic, heavy, recreational cannabis use being associated with poorer driving performance in non-intoxicated individuals compared to non-users, the researchers linked earlier onset of marijuana use (under age 16) to worse performance.

The study was conducted by McLean Hospital’s Mary Kathryn Dahlgren, PhD, Staci Gruber, PhD, and their team from McLean’s Cognitive and Clinical Neuroimaging Core and the Marijuana Investigations for Neuroscientific Discovery (MIND) program. The study, conducted through driving simulation, concluded that chronic, heavy, recreational marijuana use was associated with worse driving performance in non-intoxicated drivers compared to non-using healthy control participants.

Other findings of the study:

  • Cannabis users had more accidents, drove at higher speeds, and drove through more red lights than non-users
  • Earlier onset of marijuana use (regular use prior to age 16) was associated with poorer driving performance
Driving high, marijuana and car key isolated on white

Jennifer’s Messengers

Many American’s lose their lives each year due to impaired driving. Traffic fatalities are rising in states which have legalized marijuana. We believe this emerging danger needs to be dealt with–the public needs to be forewarned, and politicians need to consider this issue when accepting campaign contributions from the marijuana industry.

Rocky Mountain High Intensity Drug Trafficking Area

Since recreational marijuana was legalized, traffic deaths in which drivers tested positive
for marijuana increased 109 percent while all Colorado traffic deaths increased 31
• Since recreational marijuana was legalized, traffic deaths involving drivers who tested
positive for marijuana more than doubled from 55 in 2013 to 115 people killed in 2018.
o This equates to one person killed every 3 days in 2018 compared to one person
killed every 6 ½ days in 2013.
• Since recreational marijuana was legalized, the percentage of all Colorado traffic deaths
that were marijuana related increased from 15 percent in 2013 to 23 percent in 2018.


 Reader discretion is advised, content describes details of violent crimes.

Mothers Against Drunk Driving (MADD) helped wake up the country to the dangers of drunk driving. They succeeded in getting laws changed, nationwide in the United States. Now that four more states have legalized marijuana, what about stoned or high driving? Driving under the influence of a drug (DUID), is this something to be concerned about or, is it, as many stoners believe, people drive better while impaired?

Witness Video – Pickup Truck Centerline Crossover Collision with Medium-Size Bus on US Highway 83


On March 29, 2017, about 12:20 p.m., a fatal traffic collision occurred on US Highway 83 near Concan, Texas. The crash involved a 2007 Dodge Ram pickup truck traveling north on US 83 which crossed the centerline of the rural highway and collided with a medium-size bus. As a result of the crash, the bus driver and 12 passengers were fatally injured. The driver of the truck and one bus passenger sustained serious injuries. The video includes clips of a recording made by a witness in a vehicle following the pickup truck. The original video was recorded using a Samsung Galaxy S5 cell phone camera and was 14 minutes and 27 seconds in length. The video ended about 20 seconds prior to the crash. The video clips shown include a time stamp depicting the elapsed time relative to the beginning of the recording. Image stabilization software was used to reduce the motion of the camera seen in the original recording. Audio recording of the two occupants in the witness vehicle was removed. Audio Script: This video shows the operation of a pickup truck driven by a 20-year-old driver traveling north on US Highway 83 near Concan, Texas. The video shows clips from a cell phone recording made by a witness following the truck. Time stamps indicate the elapsed time from the beginning of the recording. Image stabilization software was used to reduce the motion of the camera. The audio was removed.

1. Time Stamp: 0:11 This clip shows the truck cross the centerline into the southbound lane of travel.

2. Time Stamp: 0:44 Here the truck drifts onto the right shoulder almost hitting a stopped truck.

3. Time Stamp: 3:15 The truck drives off the right road edge, recovers, and then continues to drive partially on the shoulder.

4. Time Stamp: 3:37 When the road widens to two lanes, the truck moves to the right and travels off the paved surface and onto the grass.

5. Time Stamp: 6:23 The truck moves partially onto the shoulder and then left and crosses the centerline and onto the shoulder on the opposite side of the highway.

6. Time Stamp: 6:54 The truck crosses the centerline again as it proceeds around a curve.

7. Time Stamp: 7:11 As the truck reaches a left-hand curve, it moves onto the right shoulder and then left; crossing the centerline again as the road transitions to a right-hand curve.

8. Time Stamp: 10:02 Here the truck crosses the centerline as it rounds a right-hand curve with a limited line of sight.

9. Time Stamp: 10:17 At the end of the curve, the truck moves onto the right shoulder.

10. Time Stamp: 12:04 The truck travels on the centerline rumble strips designed to alert drivers and proceeds partially into the opposing lane of travel.

11. Time Stamp: 12:56 The truck travels entirely within the opposing lane of travel on a vertical crest hill with a limited line of sight.

12. Time Stamp: 14:16 This clip shows the final ten seconds of the witness video. The recording ended about 20 seconds before the multiple fatality crash on the right-hand curve ahead.

Marijuana DUI Arrests Up 48% In Last Year Across Colorado

By CBS4 Political Specialist Shaun Boyd January 29, 2021 at 7:29 pm Filed Under:Colorado News

DENVER (CBS4)– For the first time, there’s hard evidence that more and more people are driving high in Colorado. And, the sobering statistics could impact the growing marijuana industry in our state.

While police have tracked DUIs for years, they’ve lumped them altogether, so there’s no telling which drugs are the biggest problems.

Ed Wood helped changed that with a law that requires DUI data specify the drug involved. Wood’s son Brian was killed by two women sharing the wheel of car while high. Devastated, he dedicated his life to getting marijuana impaired drivers off the road.

“There’s a large gap between actual and perceived risk imposed by THC-impaired drivers,” said Wood.

While alcohol is still the drug of choice, the Colorado Bureau of Investigation says 47% of drivers are testing positive for marijuana, followed by amphetamines and cocaine. The Colorado State Patrol says DUI arrests involving marijuana are up 48% in the last year.

“We need to do for drug impairment what we’ve already done for alcohol impairment,” said Wood.

That starts, he says, with changing the Department of Motor Vehicle Driver Handbook which states, “It is unclear whether cannabis use increases the risk of car crashes.”

According to the Colorado Department of Transportation, the number of marijuana impaired drivers involved in deadly crashes has risen every year between 2017 and 2019, the most recent years for which data is available.

Wood knows that any change won’t be easy. He’s been at it 10 years.

“There are times I give up and say, ‘I’m not doing this anymore.’”

Credit CBS

Campaign from NHTSA ad council

(National Highway Traffic Safety Administration)


Any dose of alcohol combined with cannabis significantly increases levels of THC in blood

Date:May 27, 2015

Source: American Association for Clinical Chemistry (AACC)

Summary: Cannabis plus alcohol is one of the most frequently detected drug combinations in car accidents, yet the interaction of these two compounds is still poorly understood. A study shows for the first time that the simultaneous use of alcohol and cannabis produces significantly higher blood concentrations of cannabis’s main psychoactive constituent, THC, as well as THC’s primary active metabolite than cannabis use alone.