Democrats are taking racial politics to new heights—and no wonder, since the tactic has again succeeded. This week Republican Senator Tim Scott said he will oppose the nomination of Thomas Farr, tapped for a federal judgeship in North Carolina. Senator Jeff Flake is voting no to showcase his opposition to Donald Trump, and the two GOP defections are enough to torpedo Mr. Farr’s appointment this year.

Mr. Scott cited legal work that Mr. Farr performed decades ago for North Carolina’s then-Senator Jesse Helms. After the 1990...