House Democrats are plowing ahead with an impeachment effort inspired by accusations from an anonymous “whistleblower.” The lawmakers may allow the witness to testify anonymously, sources who themselves remained anonymous told the Washington Post this week. It’s as if the whole effort is designed to confirm President Trump’s complaint that the “deep state” is determined to sabotage his presidency.

By “deep state,” Mr. Trump seems to mean any current or former federal employee who works to undermine him. I find that definition...