As usual it was well-meaning, but came with unintended consequences. This time it's drug sentencing laws, and how they vary by the form of the drug, because of a quick/knee jerk reaction to what was happening in black communities in the 1980s. If the author is right and a decent number of the people who supported the sentencing laws were black leaders who were worried about their communities, it's hard to argue it was, at least exclusively, about racism.
Or as Bryan Caplan has put it on his blog (stolen from this show, which apparently Maggie Thatcher's favorite at least for a time) Politician's logic: "Something must be done, this is something, therefore it must be done"