James Comey gave his follow-up testimony to Congress this week, in which he continued to profess memory loss about most of the 2016 investigation of the Trump campaign. Then again, the joke was on the former director of the Federal Bureau of Investigation. Thanks to two years of dogged investigation, House Republicans already know the story of the FBI’s 2016 doings. Mr. Comey wasn’t there to provide new details. He was there to account for his actions. That’s the crowning achievement of this 115th Congress. Tax and criminal-justice reform and judicial appointments are all hugely important. But House and Senate...