Donald Trump is rightly frustrated that so many in Washington and the media refuse to take seriously the evidence that the government abused its surveillance powers during the 2016 election. Still, let’s remember who the bad guys are in this story. Hint: not Attorney General Jeff Sessions or Justice Department Inspector General Michael Horowitz.

Mr. Trump’s Wednesday tweetstorm included a blast at both men after news that Mr. Sessions had asked Mr. Horowitz to look into whether the Federal Bureau of Investigation went rogue...