From 1950-1970, America introduced new mandatory minimums for possession of marijuana. First-time offenses carried a minimum of 2-10 yrs in prison and a fine of up to $20,000. They repealed these minimums in 1970 because it did jack shit to stop people smoking. The govt even recommended decriminalizing marijuana in 1970, but Nixon rejected it.
But then came The Parents. As fucking usual, parents "concerned for their children" began a years-long lobbying and marketing effort to convince the public any kind of drug was evil and harming kids. Through the 1980s their lobbying spread to all corners of the government, influencing messaging and policy. So finally in 1986, Reagan introduced new mandatory minimums for marijuana, based on amount. Having 100 marijuana plants was the same crime as 100 grams of heroin. And then they went further; if you we caught with marijuana three times, you got a life sentence. Life. For pot. In 1989, Bush Sr. officially declared the "new" War on Drugs. And we've all been paying for it ever since.