If you’re facing drug-impaired driving charges and have been using CBD, recent research offers some reassurance that you will not get an impaired driving charge. A systematic review by Lo et al. (2024) concluded that CBD use alone is unlikely to significantly impair a person in their normal activities. This finding is crucial for those who rely on CBD for medical reasons but are concerned about its potential impact on driving.
However, another study by Manning et al. (2024) raised questions about the effects of a medicinal cannabis with dominant CBD on driving-related cognitive functions. At first glance, the study seems to suggest that CBD can cause impairment in visuospatial working memory and delayed pattern recognition. But a closer look reveals that the situation is a lot more nuanced than that.
Manning et al.’s study used an unusual process to choose participants. None of the 31 participants had used cannabis, including medical cannabis, for at least a year before the study. That means that none of its subjects were reflective of real cannabis users with a tolerance to the effects of THC and its imparting effects. The results of the study are really only meaningful for people who are naive to cannabis use — which is not the majority of medical users.
But that’s not all. Manning et al.’s study reported impairment in only some cognitive areas, while others showed no sign of impairment. And the differences observed between the placebo and medical CBD treatments were within the 95% confidence intervals, suggesting the results may not be statistically significant. That is, the cognitive impairment may have been the cognitive impairment people already had and not caused by the CBD medical product in any event.
This begs the question, why did Manning et al. choose participants who were not regular cannabis users? Cynically, it may be that the authors anticipated challenges in detecting impairment among regular cannabis users due to tolerance. Choosing people who did not use cannabis routinely may have permitted them to see more effects and get more sensational results. And sensational results are great for publication. But of course, that seriously compromises the integrity of the study and its potential relevance to real-world scenarios where regular medical cannabis users are behind the wheel.
In essence, while Manning et al.’s study raises some concerns, its limitations and possibility for bias in the research are massive. The absence of impairment in several cognitive areas and the atypical participant selection process cast doubt on the study’s applicability to real-world situations.
Conversely, the findings of Lo et al. (2024) offer a more comprehensive perspective. Their systematic review, which includes a review of a broad range of studies, suggests that CBD use alone is unlikely to impair driving ability significantly. This is reassuring news for individuals who rely on CBD for medical purposes but worry about its effects on daily activities, including driving and the possibility of getting a charge for cannabis impaired driving or drug-impaired driving.
Whenever these studies are published and touted by law enforcement and government to support cannabis impaired driving laws, it is critical to weigh the evidence carefully and read the studies and their parameters closely. While individual studies may suggest potential impairment in the ability to drive by certain drugs, a comprehensive analysis like that of Lo et al. provides a more nuanced understanding.
As always, if you’re facing legal challenges related to drug-impaired driving, we can assist you and have a database of scientific studies and knowledge to effectively and comprehensively defend your case.
