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Police departments

Flawed Methods in Detecting Drugged Driving Put US Road Safety at Risk

Strategic Insights

— 1 min read

Police officers trained to detect drug-impaired drivers use methods not based on science, an editorial in the Journal of Studies on Alcohol and Drugs claims. The techniques, known as drug recognition expert (DRE) protocols, rely on subjective tactics rather than objective measures. A person's blood levels of THC, the main intoxicating chemical in marijuana, do not correlate with impairment, making the current methods unreliable.

Key Takeaways:

  • The DRE protocols used by police officers to detect drug-impaired drivers are not based on scientific evidence and are considered pseudoscience.
  • The methods rely on subjective tactics, including tests of physical coordination, blood pressure, pulse, muscle tone, pupil size, and eye movements, rather than objective measures.
  • Few scientific studies have tried to determine the accuracy of DRE protocols, but the existing evidence suggests they are "not much better than a coin toss."
  • Despite the lack of scientific evidence, DRE programs and training are federally funded, and more than 8,000 DREs work in police departments nationwide.
  • Workplace impairment recognition experts (WIREs) are also certified to detect and prevent on-the-job drug impairment, with no scientific basis.
  • A recent commentary in the Journal of Studies on Alcohol and Drugs highlights the urgent need for scientifically valid methods to detect marijuana impairment.
  • Collaborations between law enforcement and scientists are recommended to improve detection of drug-impaired driving.
  • Taxes from legal marijuana sales could be allocated to fund research on more robust tools for identifying cannabis-impaired drivers.

Statistics:

  • Over 8,000 DREs work in police departments nationwide.
  • Few scientific studies have tried to determine the accuracy of DRE protocols.
  • The existing evidence suggests DREs are "not much better than a coin toss."

Sources:

  • McNichol, W. J., (2024). Perspective: Pseudoscience and the detection of marijuana-based impairment: We can and must do better. Journal of Studies on Alcohol and Drugs, 86(4), 503-509. https://doi-org.sdpl.idm.oclc.org/10.15288/jsad.24-00307
  • Marcotte, T. D., & Fitzgerald, R. L., (2025). Robust Validation of methods for detecting driving under the influence of cannabis: Paths forward. Journal of Studies on Alcohol and Drugs, 86(4), 510-514. https://doi-org.sdpl.idm.oclc.org/10.15288/jsad.25-00110

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