We knew we couldn’t make it illegal to be either against the war or black, but by getting the public to associate the hippies with marijuana and blacks with heroin, and then criminalizing both heavily, we could disrupt those communities. We could arrest their leaders, raid their homes, break up their meetings, and vilify them night after night on the evening news. Did we know we were lying about the drugs? Of course…
Laying it all on Nixon does not explain "Reefer Madness" (1936) nor every other country that criminalizes drugs with zeal.
Prohibition is a timeless, recurring issue. I think it comes from something even more timeless: moral authoritarianism.
The urge felt by many people to force their neighbor to do things the Right Way.
The puritan dream that the world could be clean and harmonious and good if only Those People could be brought to heel.