WHY IT MATTERS: Patients who use cannabis in the evening for sleep, pain, or anxiety need accurate information about whether they are functionally safe to drive the following morning, because current legal standards often conflate cannabinoid detection with actual impairment. CLINICAL OVERVIEW: The relationship between cannabis consumption and next-day driving performance is a genuinely complex clinical and policy question, shaped by factors including frequency of use, tolerance, cannabinoid pharmacokinetics, and the wide variability in how individuals metabolize THC. Frequent cannabis users develop meaningful neuroadaptation over time, which alters both subjective intoxication and measurable psychomotor function in ways that occasional users do not experience.