A two-phase trial will test whether medical cannabis patients are actually impaired while driving at therapeutic doses, comparing their performance to alcohol impairment at the legal limit.
Medical cannabis patients who drive, traffic safety researchers, policymakers, and driving law advocates
What the researchers found
Study protocol for the first real-world on-track driving study of prescribed medical cannabis patients (n=72 across pain, anxiety, insomnia) compared to alcohol-impaired healthy controls (n=24 at 0.05% BAC), measuring lateral vehicular control.
Why it matters
Australia (and many jurisdictions) prohibit driving with any detectable THC, regardless of actual impairment — this study could provide the evidence needed to shift from zero-tolerance to impairment-based driving laws.
The numbers in context
Phase 1: 72 patients (24 each for pain, anxiety, insomnia); Phase 2: 24 healthy controls at 0.05% BAC; repeated on-track driving assessments with cognitive testing and biological sampling.
How the study worked
Two-phase trial: Phase 1 is a semi-naturalistic cohort study of 72 medical cannabis patients completing on-track driving assessments; Phase 2 is a randomized, placebo-controlled crossover study of 24 healthy participants with alcohol.
What this study cannot tell us
Study protocol only (no results yet); on-track driving differs from real-world conditions; single-dose assessment may not capture cumulative or chronic use effects.
How to read the evidence
Published study protocol with registered trials, but no results yet — significance lies in the novel design addressing a critical policy gap.
When this study was published
Published in 2026, trials registered in 2024, representing the cutting edge of medical cannabis driving research.
The bigger picture
This addresses one of the most contested questions in cannabis policy: are medical cannabis patients who use THC products as prescribed actually unsafe to drive? Current laws assume yes, but evidence is lacking.
Questions still open
- Will medical cannabis patients show comparable impairment to alcohol at the legal limit? Should driving laws distinguish between recreational and therapeutic cannabis use?
Common questions
Does medical cannabis impair driving ability?
How does this study compare cannabis to alcohol impairment?
Read the original research
Effects of prescribed medical cannabis and alcohol on real-world driving performance (CAN-TRACK): a study protocol for a two-phase trial.
Trials
Citation
Arkell, Thomas R; Hayley, Amie C; Aitken, Blair; Hu, Xinyun; Manning, Brooke; Downey, Luke A. (2026). Effects of prescribed medical cannabis and alcohol on real-world driving performance (CAN-TRACK): a study protocol for a two-phase trial.. Trials. https://doi.org/10.1186/s13063-026-09512-x