WHY IT MATTERS: If you use cannabis medicinally and drive, better research into impairment testing could eventually replace unreliable THC blood level thresholds with assessments that more fairly and accurately reflect whether you are actually safe behind the wheel. CLINICAL OVERVIEW: As cannabis legalization continues to expand across the United States, research into how cannabis use affects driving performance remains critically underdeveloped, creating a significant gap between policy and patient safety evidence. New approaches to studying cannabis-impaired driving are essential because unlike alcohol, THC affects psychomotor function in highly variable ways depending on tolerance, dosing method, cannabinoid profile, and individual metabolism.