Jay Evensen implies that regulating the adult consumption of marijuana will lead to an uptick in adolescents’ access and use of the substance (“Marijuana acceptance will lead to social costs,” Aug. 21). He writes: Legalization advocates “would prohibit use by anyone under 21, naively thinking legalization for adults would not trickle down to teenagers.”

Evensen presumes that criminalization of cannabis will somehow prevent pot from trickling down into the hands of young people. However, America’s nearly 100-year experience with marijuana prohibition demonstrates that this presumption to be incorrect.

By contrast, public policies regulating alcohol and tobacco — two substances that are objectively more harmful than marijuana — have proven to be far more effective at reducing teens’ access. According to federal government figures, self-reported alcohol consumption within the past 30 days among 12th graders has fallen from 75 percent in the late 1970s to 40 percent today. Tobacco use among 12th graders has similarly dropped, from 28 percent in the 1990s to just 16 percent today. These outcomes were not accomplished by instituting criminal prohibition, but rather by legalization, regulation and public education.

Paul Armentano

Washington, D.C.