It's applied disproportionately to black and hispanic people. How many wall street bankers, who take more cocaine than anyone in prison has ever even seen is actually behind bars? It was a ramping up the drug war, which targets the drugs that minorities take more than white people. And it's led to the private prison complex, which relies on fresh prisoners to maintain growth. And they're not going to put the white boys in prison, because that'd mean the congressmens and senators kids go to prison.
It actually started with Harry Anslinger claiming Marijuana makes hispanic people aggressive, and it's led to America having more people imprisoned than any other country in the world. Almost 100 years of prohibition because a racist dickwad lost his anti-boozing job.