Forgotten in all the media drama and confused White House communications of recent months was the fact that the President had several very good reasons for firing FBI Director James Comey in May. Now comes evidence of another one.

On Wednesday Senate Judiciary Committee Chairman Chuck Grassley of Iowa and Sen. Lindsey Graham of South Carolina wrote to current FBI Director Christopher Wray asking for additional documents related to Mr. Comey’s decision to exonerate Hillary Clinton in 2016. FBI agents had been investigating...