Special counsel Robert Mueller’s investigation captivated Washington for nearly two years. Much of the media focused on speculation and fuzzy allegations, fueled by critics eager to pronounce the president’s guilt, of coordination between the Trump campaign and the Kremlin. After an exhaustive investigation, many of those same critics still struggle to accept that Mr. Mueller and his investigative team of Democratic donors found no collusion and charged the president with no crime.

The Mueller report goes far beyond the debunked...