Summary:

- The study found no linear relationship between blood THC levels and driving impairment, challenging the assumption behind many state laws that set a specific THC limit to determine marijuana-impaired driving.
- The researchers argue that using a per se THC limit to determine impairment is problematic, as THC levels can vary significantly between individuals and over time, and do not necessarily correlate with functional impairment.
- The findings suggest that more nuanced, evidence-based approaches are needed to assess marijuana-related impairment, rather than relying solely on blood THC levels, which may not accurately reflect a person's level of impairment.