The 'drug war' has always been intended to treat black and white users differently (and consequently the drugs they tend to reach for differently, not the other way around as many people assume); in many ways that was the whole point. See this article from Harpers [1]:
> I’d tracked Ehrlichman, who had been Nixon’s domestic-policy adviser, to an engineering firm in Atlanta, where he was working on minority recruitment. At the time, I was writing a book about the politics of drug prohibition. I started to ask Ehrlichman a series of earnest, wonky questions that he impatiently waved away.
> “You want to know what this was really all about?” he asked with the bluntness of a man who, after public disgrace and a stretch in federal prison, had little left to protect. “The Nixon campaign in 1968, and the Nixon White House after that, had two enemies: the antiwar left and black people. You understand what I’m saying? We knew we couldn’t make it illegal to be either against the war or blacks, 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 we did.”
Or maybe there might be an other confounder than skin color ? Maybe SES status of drug addict influences the way they finance their habit You might want to compare the impact of crack in black neighborhoods on violent crime and the impact of opioids in white neighborhoods on violent crime. Assuming the justice/police system is actually concerned about violent crimes, Occam's razor shaves off the racist assumptions pretty nicely. Also cf. Locking up our own https://www.nytimes.com/2017/04/11/books/review-locking-up-o...
+1 for Locking up Our Own - really interesting study of how the crack war led to massive incarceration of black youth, using DC as the primary case study
> I’d tracked Ehrlichman, who had been Nixon’s domestic-policy adviser, to an engineering firm in Atlanta, where he was working on minority recruitment. At the time, I was writing a book about the politics of drug prohibition. I started to ask Ehrlichman a series of earnest, wonky questions that he impatiently waved away.
> “You want to know what this was really all about?” he asked with the bluntness of a man who, after public disgrace and a stretch in federal prison, had little left to protect. “The Nixon campaign in 1968, and the Nixon White House after that, had two enemies: the antiwar left and black people. You understand what I’m saying? We knew we couldn’t make it illegal to be either against the war or blacks, 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 we did.”
[1] https://harpers.org/archive/2016/04/legalize-it-all/