Cannabis Users on the Road: A Hazy Picture of Knowledge and Law Enforcement
Majority of Cannabis Consumers Take Wheel on Same Day of Use
A new report from the AAA Foundation for Traffic Safety reveals some startling truths about cannabis use and driving in the US. Despite cannabis becoming more accessible across many states, a majority of users are flouting laws by getting behind the wheel after consuming.
The survey, which questioned 2,000 cannabis users across eight states, highlighted a damning statistic: a staggering 84.8% of consumers reported that they drive the same day they consume cannabis. This number drops slightly in fully legal states but remains concerning.
When asked about law enforcement's ability to detect cannabis-impairment, only 29.2% of participants believed an officer could detect the influence, while 46.7% didn't think they could and 24.1% remained unsure. This pattern was consistent across all states.
The survey divided users into categories based on driving risk, with 53% categorized as ultra-high risk (consuming within an hour before driving), 20% high risk (consuming 2-3 hours prior), 12% medium risk (consuming 4+ hours but still on the same day without sleep), 15% low risk (waiting at least 8 hours and sleeping before driving), and the remaining 10% falling into other categories.
When it comes to messaging that could sway users to avoid driving under the influence, the message "If you feel different, you drive different- Drive High. Get a DUI" was the most effective. This message prompted 62% to say they'd wait longer before driving and 58% to consider alternative transportation options. However, only 20-29% were likely to reduce their cannabis consumption.
Unclear Link Between Cannabis and Accidents
These findings align with a similar survey published by the AAA in 2019, which reported that 14.8 million motorists said they drive within an hour of using cannabis.
Another study by The Zebra, an insurance comparison platform, revealed that 51% of drivers in legal cannabis states decide whether to drive based on how they feel. This decision often leads to impaired abilities, with 47% reporting such effects, yet only 35% were familiar with their state's cannabis driving laws.
However, assessing the impact of cannabis on motor vehicle fatalities is complex. In 2021, a study published in the American Journal of Public Health found that between 2000 and 2018, the percentage of fatalities involving cannabis increased from 9% to 21.5%.
Considering motor vehicle collisions that occurred in the presence of cannabis impairment, a study published in the journal Accident Analysis and Prevention in 2024 examined over 1,300 patients recruited from emergency departments in three legal cannabis states. The study revealed that cannabis alone was not associated with higher odds of collisions, while acute alcohol use alone and the combination of alcohol and cannabis were both independently associated with higher odds of collisions.
Law Enforcement Struggles to Detect Cannabis-Impaired Driving
The challenges in detecting cannabis-impaired driving are significant. Unlike alcohol, the effects of cannabis vary depending on the method of consumption, with smoking producing a quick but short-lived effect, while edibles take longer to kick in and last longer.
Some states have implemented innovative methods like THC saliva tests and cognitive assessment apps to detect impairment more effectively. States like Colorado have enacted laws that allow for an inference of impairment if THC is detected, but not necessarily at a specific threshold.
However, the lack of a clear correlation between THC concentration and impairment (unlike alcohol) makes enforcement challenging and reliant on officer training and roadside observations.
State-Specific Laws and Approaches
While the laws and attitudes towards cannabis vary across the U.S., some states have taken proactive approaches to address cannabis-impaired driving. For instance, Colorado has a permissible inference law for THC, meaning that if THC is detected, it can be inferred that the driver was impaired. Colorado also conducts "green labs" to train officers to recognize signs of impairment. Minnesota conducted a pilot program using saliva tests to detect THC in drivers.
Despite these initiatives, the lack of a uniform standard for THC impairment remains a growing issue. A clear understanding of the relationship between THC concentration and impairment would greatly aid law enforcement in combating cannabis-impaired driving effectively.
- Motorists continue to flout laws by driving after consuming cannabis, despite the growing accessibility of the substance across many states.
- Prevention messages, such as "If you feel different, you drive different- Drive High. Get a DUI," have shown some success in persuading users to wait longer before driving and consider alternative transportation options.
- Assessing the impact of cannabis on motor vehicle fatalities is complex, with studies showing that the percentage of fatalities involving cannabis has increased over the years, but the relationship between THC concentration and impairment remains unclear, making proper enforcement challenging.
