When historians look back, I fear they’ll view the events of Charlottesville, Va., as a turning point, a crossing-the-Rubicon moment that preceded the inevitable fall of a great civil right. Free speech is a right—a privilege, really—with an uncertain fate. The outcropping of press clippings questioning the efficacy and morality of unencumbered expression are a portentous sign. The protection guaranteed by the First Amendment has always been threatened, or curtailed, in our country’s history. What transpired on the streets of Charlottesville is different. The gratuitous killing of Heather Heyer was awful enough–but it also provided plenty of fodder for those...