Many medications, like benzodiazepines, opioids, and antibiotics can lead to impairment. We do not prospectively penalize patients who use these substances. We expect that patients monitor their own impairment and not drive when incapable.
This policy can also be found in pdf form here.
What Does The Data Say?
In general, studies demonstrate significant impairment from the acute use of cannabis, but significantly worse impairment from alcohol or when alcohol is used concurrently with cannabis. While low doses can be significantly impairing, higher doses, as would be typically seen in recreational users compared to medical users, are more impairing. Chronic users, as would be the case of most medical users, are less affected than intermittent users (3,4,5). Further, studies show that driving is safe approximately 4 hours after a dose by inhalation and 6 hours after a dose by oral ingestion (1,2,6).
When Should DUI Be Applied?
DUI cannabis should be applied only in setting of demonstrable impairment of a driver that leads to another moving violation. For example, speeding, failure to stop at red light or stop sign, or unsafe lane change. Possession of a medical card, legal possession of cannabis, or even suspicion of impairment without other infraction should not lead to prosecution.
1) Marcotte, T. D., Umlauf, A., Grelotti, D. J., Sones, E. G., Sobolesky, P. M., Smith, B. E., … Fitzgerald, R. L. (2022). Driving Performance and Cannabis Users’ Perception of Safety. JAMA Psychiatry. https://doi.org/10.1001/jamapsychiatry.2021.4037
2) Ogourtsova, T., Kalaba, M., Gelinas, I., Korner-Bitensky, N., & Ware, M. A. (2018). Cannabis use and driving-related performance in young recreational users: a within-subject randomized clinical trial. CMAJ Open, 6(4), E453–E462. https://doi.org/10.9778/cmajo.20180164
3) Arkell, T. R., Spindle, T. R., Kevin, R. C., Vandrey, R., & McGregor, I. S. (2021). The failings of per se limits to detect cannabis-induced driving impairment: Results from a simulated driving study. Traffic Injury Prevention, 1–6. https://doi.org/10.1080/15389588.2020.1851685
4) Arkell, T. R., Vinckenbosch, F., Kevin, R. C., Theunissen, E. L., McGregor, I. S., & Ramaekers, J. G. (2020). Effect of Cannabidiol and d9-Tetrahydrocannabinol on Driving Performance: A Randomized Clinical Trial. JAMA - Journal of the American Medical Association, 324(21), 2177–2186. https://doi.org/10.1001/jama.2020.21218
5) Sewell, R. A., Poling, J., & Sofuoglu, M. (2009). The effect of cannabis compared with alcohol on driving. The American Journal on Addictions, 18(3), 185–193. https://doi.org/10.1080/10550490902786934
6) McCartney, D., Arkell, T. R., Irwin, C., & McGregor, I. S. (2021). Determining the magnitude and duration of acute Δ9-tetrahydrocannabinol (Δ9-THC)-induced driving and cognitive impairment: A systematic and meta-analytic review. Neuroscience & Biobehavioral Reviews, 126, 175–193. https://doi.org/10.1016/J.NEUBIOREV.2021.01.003