Finally America has its George Smiley, the fictional master spy from the John le Carré novels. Smiley knew the importance of a spy agency being willing to get to the bottom of its own major cock-ups.

Attorney General William Barr has been given power by Donald Trump to declassify classified material. He told CBS that stories offered by the FBI about its investigation of the Trump campaign don’t “hang together.” The same could be said for a more consequential enigma of the 2016 election, concerning the alleged Russian intelligence that lay behind the FBI’s intervention in the Hillary Clinton email case.

Remind yourself what happened: James Comey, on his sole initiative, held a press conference to announce that, though Mrs. Clinton had behaved improperly, she did not merit prosecution. Except it wasn’t his decision to make: It was the Justice Department’s.

We know that Mr. Comey secretly explained his action by invoking still-classified Russian intelligence. In his memoir, he refers to a development “unknown to the American public to this day.” In fact, we know from news leaks that a Russian intercept of some kind cited a Democratic Party email that referred to an alleged conversation in which Attorney General Loretta Lynch promised to bury the Hillary Clinton investigation.

On the surface, the Russian intelligence indicated political corruption at the Justice Department and yet Mr. Comey rejected this self-advertised significance. He didn’t investigate. He didn’t tell the Justice Department. He used his possession of the classified intercept as his classified justification for intervening to free Mrs. Clinton from the email matter in time for the Democratic Convention.