Drug-impaired driving continues to be a major traffic safety challenge across the United States. As drug trends evolve and forensic technologies advance, toxicology laboratories must continuously adapt their testing practices to identify substances that may contribute to impaired driving and fatal crashes.
A recently published update to the National Safety Council Alcohol, Drugs and Impairment Division (NSC-ADID) recommendations outlines important changes for toxicological investigations in drug-impaired driving (DUID) and motor vehicle fatality cases. These recommendations are based on a 2024 survey of 80 forensic toxicology laboratories and a nationwide consensus review by experts in the field.
Why These Recommendations Matter
For years, one of the biggest challenges in impaired driving investigations has been the lack of consistency among forensic laboratories. Different testing scopes, analytical methods, and reporting practices can make it difficult to compare data across jurisdictions and fully understand the scope of drug-impaired driving.
The updated recommendations seek to:
- Standardize testing practices nationwide.
- Improve the detection of drugs commonly associated with impairment.
- Encourage laboratories to adopt current technologies and best practices.
- Provide more reliable data for law enforcement, prosecutors, policymakers, and traffic safety professionals.
What Did the Survey Reveal?
The 2024 survey showed that forensic toxicology laboratories are increasingly using advanced analytical technologies.
Among responding laboratories:
- 96% test blood samples in impaired driving investigations.
- 68% test urine.
- Only 5% routinely test oral fluid.
Another notable finding was the continued rise of fentanyl in DUID casework. In 2016, only 26% of laboratories reported fentanyl among their top detected drugs. By 2024, that number had climbed to 89%. Other substances increasing in prevalence include methadone, diphenhydramine, and novel benzodiazepines.
The drugs most encountered by laboratories included:
- Amphetamine and methamphetamine
- Cocaine
- THC
- Alprazolam
- Fentanyl
- Diazepam
- Oxycodone
- Clonazepam
- Gabapentin
Moving Beyond Urine Testing
Perhaps the most impactful recommendation is the removal of urine as a recommended matrix for impaired driving investigations.
The authors emphasize that urine often reflects historical drug use rather than recent use associated with impairment. A positive urine result may indicate exposure days earlier and may not be relevant to the driver’s condition at the time of the incident.
Instead, laboratories are encouraged to prioritize:
- Blood testing
- Oral fluid testing
These biological samples better reflect recent drug use and may be more useful when evaluating potential impairment near the time of driving.
Growing Interest in Oral Fluid Testing
Oral fluid is gaining attention as a practical alternative to blood collection.
Advantages include:
- Non-invasive collection.
- Collection close to the time of driving.
- No need for medical personnel.
- Strong correlation with recent drug use.
- Similar detection window to blood.
Although many U.S. jurisdictions have not yet implemented oral fluid testing programs, interest continues to grow, and several states have already established successful programs.
Challenges Remain
Despite significant progress, laboratories continue to face obstacles that can slow adoption of updated testing recommendations.
Common challenges include:
- Staffing shortages.
- Limited laboratory space.
- Budget constraints.
- Instrument capacity.
- Analyst training needs.
- Time required to validate new testing methods.
The survey also found that many laboratories continue to use “stop-limit testing,” a practice where drug testing may not proceed if alcohol levels exceed a predetermined threshold. Experts note that this can result in underreporting the true prevalence of drug involvement in impaired driving cases.
Looking Ahead
The 2025 update reflects both changing drug trends and advances in forensic science. While the list of commonly encountered drugs has remained relatively stable, emerging substances, fentanyl-related compounds, novel psychoactive substances, and semi-synthetic cannabinoids continue to challenge laboratories.
The authors conclude that routine testing limited to only the most common drugs may not always provide the full picture. Laboratories should regularly review their testing scope, communicate capabilities with stakeholders, and remain flexible as drug use patterns continue to evolve.
Source:
Amanda L D’Orazio, Amanda L A Mohr, Ayako Chan-Hosokawa, Curt Harper, Marilyn A Huestis, Sarah Kerrigan, Jennifer F Limoges, Amy K Miles, Colleen E Scarneo, Karen S Scott, Barry K Logan, Recommendations for toxicological investigation of drug-impaired driving and motor vehicle fatalities—2025 update, Journal of Analytical Toxicology, Volume 50, Issue 1, January 2026, bkaf085, https://doi.org/10.1093/jat/bkaf085
