It stands to reason that, if you’re going to choose a figure to shame demonstrators into emulating, you’d have a stronger case if both major political parties hadn’t spent decades fighting to dismantle his signature achievements. From the Reagan-era alignment of federal Republicanism against civil-rights enforcement to the retrenchment of school segregation and expansion of the carceral state — both of which were abetted and often spearheaded by Democrats — few civil-rights gains for black people have evaded a more or less sustained assault since they were first secured. Among the most severe manifestations has been the GOP’s war on the franchise. One of the two most s…