Highlights • Cannabis likely decreases mean speed and headway in young drivers. • Cannabis likely increases youth’s reaction time and variability of lane and steering wheel position.

Abstract Background Young drivers ages 15–24 continue to constitute a high-risk population for fatal motor vehicle collisions (MVCs) compared to all other age groups. Driving under the influence of cannabis is an important contributor to the high rates of MVCs among youth. Understanding the specific impact of cannabis on the driving performance outcomes of young drivers can inform injury prevention, education, and intervention strategies. Objectives This systematic literature review (SLR) aims to determine the Class (I- highest to IV-lowest) of evidence and level of confidence (A-high to U-insufficient) in the effects of cannabis on the driving performance of young drivers. Methods Registered in PROSPERO (#CRD42020180541), this SLR searched seven data bases and appraised the quality and confidence in the evidence using an established research methodology. Results Class II evidence suggests that THC is likely to reduce mean speed and increase headway distance; and increase reaction time, lane, and steering wheel position variability among young drivers (Level B, moderate confidence). Conclusions This study shows that there is a moderate to low level of confidence on the impact of cannabis on the specific driving performance outcomes of young drivers. A need remains for Class I and II studies that focus on the specific effects on young drivers, distinguish between the biological and socially constructed variables of sex and gender, and includes larger and more representative samples.