“In the United States, 33 states and the District of Columbia have passed medical marijuana laws (MMLs), while 10 states and the District of Columbia have legalized the recreational use of marijuana.
A 2018 meta-analysis concluded that the results from previous studies do not lend support to the hypothesis that MMLs increase marijuana use among youth, while the evidence on the effects of recreational marijuana laws (RMLs) is mixed.
Here, we report estimates of the association between the legalization of marijuana and its use, simultaneously considering both MMLs and RMLs.
Consistent with the results of previous researchers, there was no evidence that the legalization of medical marijuana encourages marijuana use among youth.
Moreover, the estimates reported in the Table showed that marijuana use among youth may actually decline after legalization for recreational purposes.
This latter result is consistent with findings by Dilley et al and with the argument that it is more difficult for teenagers to obtain marijuana as drug dealers are replaced by licensed dispensaries that require proof of age.”