Minneapolis’s 3rd police precinct headquarters in flames. Stephen Maturen/Getty Images.

Two weeks ago in these pages I wrote about the murder of Ahmaud Arbery, a young black man gunned down in cold blood by a trio of south Georgia rednecks in a town near my old high school. As I noted, the murder was horrific enough, though not surprising, as it was part of a long and vile history. But the real outrage was the blithe decision of the local authorities not to charge the killers until public outcry forced a reversal. (One of the accused was affiliated…