" Table 8-8 lists the proportions of 12th graders in 2019 who favor various legal consequences for marijuana use. The proportion who believe it should be entirely legal was 51%, the highest level recorded by the survey. As the percentage favoring legality increased, the percentage believing marijuana use should be a crime decreased and in 2019 was 9%, the lowest level recorded by the survey, having fallen from a peak of 53% in 1990.
" Asked whether they thought it should be legal to sell marijuana if it were legal to use it, about two in three (67%) said “yes,” matching the historic high of 67% set in 2017. However, about 87% of those answering “yes” (58% of all respondents) would permit sale only to adults. A small minority (9%) favored the sale to anyone, regardless of age, while 20% said that sale should not be legal even if use were made legal, and 13% said they “don’t know.” Thus, while the majority now subscribe to the idea of legal sale, if use is allowed, the great majority agree with the notion that sale to underage people should not be legal.
" Most 12th graders felt that they would be little affected personally by the legalization of either the sale or the use of marijuana. Forty-three percent of the 2019 respondents said that they would not use the drug even if it were legal to buy and use, while others indicated that they would use it about as often as they do now (17%) or less often (1%). Only 10% said they would use it more often than they do at present, while 17% thought they would try it. Another 12% said they did not know how their behavior would be affected if marijuana were legalized. Still, this amounts to 27% of all 12th graders, or about one in four, who thought that they would try marijuana, or that their use would increase, if marijuana were legalized.
" A study of the effects of decriminalization by several states during the late 1970s, based on MTF data, found no evidence of any impact on the use of marijuana among young people, nor on attitudes and beliefs concerning its use.18 However, it should be noted that decriminalization falls well short of the full legalization posited in the questions here. Moreover, the situation today is very different from the one in the late 1970s, with more peer disapproval and more rigorous enforcement of drug laws, at least until recently. Some more recent studies suggest that there might be an impact of decriminalization, because “youths living in decriminalized states are significantly more likely to report currently using marijuana.”19 One study using MTF data shows that prevalence of marijuana use among 12th grade Californian students significantly increased in the two years after decriminalization went into effect in 2011, and youth attitudes also became significantly more permissive.20 As more states approve full legalization of recreational use for adults (as has occurred in California, Illinois, Massachusetts, Michigan, Nevada, Maine, Colorado, Washington, Oregon, Alaska, Vermont, and Washington, DC), it is possible that attitudes about, and use of, marijuana will change. Declines in perceived risk and disapproval of marijuana would seem the most likely attitudinal changes, and such changes may well lead to increased use among youth."
Miech, R. A., Johnston, L. D., O’Malley, P. M., Bachman, J. G., Schulenberg, J. E., & Patrick, M. E. (2020). Monitoring the Future national survey results on drug use, 1975–2019: Volume I, Secondary school students. Ann Arbor: Institute for Social Research, The University of Michigan.