Partisans of Hillary Clinton insist the public has too much information about the FBI’s various inquiries into the Democratic presidential nominee and her associates. On its face, that claim seems reasonable. After all, Anthony Weiner is involved.

On Friday we learned, from director James Comey’s letter to Congress, that the FBI is once again investigating Mrs. Clinton’s illicit private email server. Two days later (and also in today’s print edition) The Wall Street Journal published a thorough report by Devlin Barrett revealing...