<p>Cannabis use has increased in tandem with expanding legalization. However, the impact of medical cannabis legalization on cannabis use disorder (CUD) and driving under the influence of cannabis (DUIC) remains unclear, as is whether specific subpopulations have been particularly affected by such laws. National Survey on Drug Use and Health (NSDUH) data from 2016 to 2019 were used, in which respondents completed interviews identifying the following outcomes: (a) whether they had used cannabis in the previous 30 days, (b) met diagnostic criteria for CUD, and (c) engaged in DUIC in the past 12 months. Propensity-score weighting was used to balance respondents from states where cannabis is legal for medical purposes with respondents from states where it is not. Each of the above three outcomes were modeled via logistic regression as a function of state cannabis policy and stratified by age, sex, and race/ethnicity. State-level medical cannabis legality was associated with statistically greater rates of cannabis use (2.3% difference), CUD (0.3% difference), and DUIC (0.4% difference), all <i>p</i>s&lt;0.001. These findings were consistently observed across nearly all age, sex, and racial/ethnic identity groups but were particularly acute among young adults and Native American and Alaskan Native respondents. These findings underline a potential association of medical cannabis legalization with increased rates of past-30-day cannabis and clinically detrimental cannabis use, as well as cannabis-impaired driving. Identifying long-term impacts of these laws and heterogeneity in their effects is crucial.</p>