Press Releases

Hickenlooper Calls on DOT to Complete Report on Marijuana-Impaired Driving Research

Nov 16, 2022

Report related to researching marijuana-impaired driving was mandated as part of the Bipartisan Infrastructure Law one year ago

WASHINGTON – U.S. Senator John Hickenlooper requested an update from the Department of Transportation (DOT) on the status of a report identifying federal barriers to researching the effects of marijuana-impaired driving. Under the Bipartisan Infrastructure Law, which Hickenlooper helped write, DOT is required to submit a report to Congress by November 2023 that identifies federal statutory and regulatory barriers to the conduct of scientific research on marijuana-impaired driving.

“The report required by Section 25026 of the IIJA is a critical first step to identify the barriers that prevent the development of an impairment standard for driving after consuming marijuana,” wrote Hickenlooper. “As implementation of IIJA continues, I would like to understand the progress made to date to produce the report on marijuana research required by the statute.”

Due to marijuana’s classification as a controlled substance on a federal level, researchers face many significant barriers to the research of marijuana’s effects. For marijuana-impaired driving in particular, federal researchers’ ability to evaluate marijuana’s effects on a driver’s performance, develop tests to accurately detect the presence of THC in a driver’s body, or determine what levels of THC constitute an impairment have been significantly restricted.

Eighteen states have laws pertaining to marijuana and impaired driving, but Colorado is the only state where a driver who surpasses a 5 nanogram THC concentration level can be penalized for driving under the influence (DUI). The report is supported by the National Safety Coalition and Advocates for Highway & Auto Safety.

“While we know that the use of marijuana is impairing, we do not have a national standard for marijuana impaired driving.  We urge the U.S. Department of Transportation (DOT) to move forward with the report on marijuana research which Sen. Hickenlooper advanced in the Infrastructure Investment and Jobs Act (IIJA) to help further the identification of a standard.  The DOT also must establish safety standards for lifesaving vehicle safety technology including impaired driving prevention technology and automatic emergency braking (AEB) to reduce the intolerable motor vehicle crash death and injury toll.  On the one-year anniversary of the law’s signing with fatalities escalating, the urgency to take action is clear,” said Cathy Chase, President of Advocates for Highway and Auto Safety.

“Multi-substance impaired driving is an epidemic on our roadways, and we need more information to help solve it. Sen. Hickenlooper led an important provision to expand marijuana impaired driving data that is key to creating needed solutions,” said Jenny Burke, vice president of impairment practice at National Safety Council. “As we mark the one year anniversary of the IIJA, I hope NHTSA moves quickly to implement this provision, which could impact safety well beyond the roadways.”

Full text of the letter is available HERE and below: 

Dear Acting Administrator Carlson:

I write to you regarding the Biden Administration’s ongoing efforts to implement the Infrastructure Investment and Jobs Act’s (IIJA) provisions to improve roadway safety for all Americans. The anniversary of this historic law represents an opportunity to celebrate the results IIJA is delivering to the American people to increase critical infrastructure resiliency against climate change, improve mobility, and enhance safety for motorists and pedestrians. As implementation of IIJA continues, I would like to understand the progress made to date to produce the report on marijuana research required by the statute.

Preventing distracted or impaired driving is a key step towards the goal of reducing traffic fatalities and improving roadway safety. In 2021, nearly 43,000 fatalities occurred from motor vehicle crashes, which is among the highest annual totals in decades. While the IIJA includes many laudable provisions to establish performance standards for crash avoidance technologies, evaluate monitoring systems to reduce distracted driving, and issue rules to detect a driver’s impaired status, many ambiguities around defining marijuana-impaired driving underscore the importance of clarifying this policy uncertainty.

Recent federal studies by the National Highway Traffic Safety Administration (NHTSA), National Academies of Sciences (NAS), and the National Institute of Health (NIH) reviewed the impact of marijuana-impaired driving within the limits of current federal law. These studies, however, were limited to surveys of existing academic literature and therefore only produced findings that are unable to be independently verified scientifically by the agency. Due to the statutory classification of marijuana as a controlled substance, federal researchers face barriers not only to evaluating marijuana’s effects on a driver’s performance, but also in developing tests to accurately detect the amount of THC in a driver’s body or determine a THC impairment level.

The report required by Section 25026 of the IIJA is a critical first step to identify the barriers that prevent the development of an impairment standard for driving after consuming marijuana. Once these barriers are identified, informed by interagency consensus, Congress would have a suite of policy recommendations to consider and implement that further advance our shared goal to prevent impaired driving and reduce roadway fatalities.

I look forward to learning about NHTSA’s progress to develop the interagency report on barriers to researching marijuana-impaired driving. Please do not hesitate to contact my office if we can offer any support toward completing this report. Thank you for your attention to this important manner.



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