Please use this link to access this publication. ABSTRACT Aims Medical marijuana law (MML) enactment in the United States has been associated with increased cannabis use but lower traffic fatality rates. We assessed the possible association of MML and individual-level driving under the influence of cannabis (DUIC) and also under the influence of alcohol (DUIA). Design and setting Three cross-sectional U.S. adult surveys: The National Longitudinal Alcohol Epidemiologic Survey (NLAES; 1991–1992), the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; 2001–2002), and the NESARC-III (2012–2013). Participants The total n was 118 497: 41 764, 41 184, and 35 549 from NLAES, NESARC, and NESARC-III, respectively. Measurements Across the...