The closer we look at the FBI’s investigative file on Hillary Clinton’s emails, the more we wonder if Director James Comey always intended to let her off the hook. The calculated release before the long Labor Day weekend suggests political favoritism, and the report shows the FBI didn’t pursue evidence of potential false statements, obstruction of justice and destruction of evidence.

Mr. Comey’s concessions start with his decision not to interview Mrs. Clinton until the end of his investigation, a mere three days before he...