Federal highway safety officials have long tracked the role of alcohol in fatal crashes, but they do not track deaths involving a driver under the influence of drugs.

Why it’s important: A 2022 National Transportation Safety Board report showed that in a sample of 26,000 drivers, about half of those arrested for impaired driving and more than a quarter of drivers killed in crashes tested positive for more than one substance. But only four states and DC drug tested more than 60% of fatally injured drivers in 2020.

The details: Several factors contribute to this…

Challenges of proving impairment: Some drugs remain detectable in a person’s system for weeks after use, making it difficult to determine impairment. While there are instant tools that can test blood alcohol level, there are no such tools or standards for impairment for other substances.
Lacking data: There are barriers to establishing a comprehensive, nationwide dataset on impaired driving. Fatality and injury reports submitted to the database often feature missing or erroneous data. Varying state laws around testing for drugs make getting uniform data difficult, as does the lack of proven metrics to measure drug impairment. An interim system that uses data from trauma centers to create a national sample of crash-involved impaired drivers is useful for public awareness and tailoring enforcement, but some centers lack the research infrastructure for round-the-clock drug testing and participation.
Federal workforce and funding cuts: The Trump administration’s cuts to the federal workforce and dwindling federal investments have slowed efforts to track impaired driving. The National Highway Traffic Safety Administration (NHTSA) grew from 600 employees to 790 from 2021 to 2024, but it had dropped to about 550 by the end of 2025. The 2021 infrastructure law increased funding for the NHTSA state highway safety program and included $750 million to modernize crash-data programs, but over $475 million was unused as of January and is expiring.