" Support for laws prohibiting consumption of marijuana in private has been in substantial decline since 1990 and has fallen by more than half from a high of 56% (in 1990) to 21% in 2019, the lowest level recorded by the survey. This trend is almost a mirror image of the pattern before 1990, when the proportion who believed private marijuana use should be prohibited more than doubled, from 25% in 1978 to its level of 56% in 1990 – also a dramatic shift. The trend for prohibition of marijuana use in public follows very closely the same overall pattern seen for private use, with support for prohibition of public use running about 30 percentage points higher in every year. In 2019 it was 49%, the second lowest level ever recorded by the survey (the lowest was in 2018 at 48%).
" In 2019 the proportions of 12th grade students agreeing that use of LSD, heroin, and amphetamines in private should be prohibited by law continued their long declines and were near historic lows (Table 8-7). The decline has been weakest for heroin, which seems to have maintained its reputation as a very dangerous drug, and support for legal prohibitions against its use in private stood at 68% in 2019. Steeper declines have been apparent for LSD and amphetamines. For all three drugs, the trends for support of legal prohibitions against public use are similar to their trends for private use, although levels of support of legal prohibitions against public use are higher and are 60% or above in all years. Specifically, in 2019 all three drugs – LSD, heroin, and amphetamines – were at or near the lowest levels recorded by the survey.
" The proportion of 12th graders who said smoking cigarettes “in certain specified public places” should be prohibited by law was 36% in 2019, a historic low. The proportion has dipped below the 40% level where it had hovered since 2013. In earlier years level of support hovered at around 45% since the 1980s and showed surprisingly little change given the steady decline in smoking prevalence over the course of the survey. Given recent widespread prohibitions of smoking in many public and private places, it is possible that the assumed definition of “certain specified public places” has expanded in the minds of many 12th graders.
" Attitudes about the legality of drunkenness in public significantly declined in 2019 to 41%, a historic low. In the past decade the percentage of 12th grade students favoring prohibition of public drunkenness had varied within the narrow range of 46% to 50%. This historic low in 2019 joins historic lows in attitudes toward both smoking cigarettes and marijuana use in public, suggesting a growing, general opposition to legal prohibition of public drug use, at least for the most commonly used substances. For private drunkenness, support for a prohibition ranged from 19% to 23% over the past decade, and in 2019 registered at 21%."
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.