The second assumption involving the supposedly long duration of the email review was also flawed. First, by prioritizing a review of the few thousand new BlackBerry emails for smoking guns, a small number of seasoned investigators could have carefully looked at them in hours, not days or weeks.

Second, like other organizations that regularly review enormous amounts of stored electronic data, the F.B.I. possessed the technical means to determine quickly whether the haul of other emails on the Weiner laptop were backup duplicates of ones already in its possession, as the vast majority apparently turned out to be. Off-the-shelf software was available to compare the Weiner laptop emails against the F.B.I.’s existing collection to exclude duplicates from the review.

What was Mr. Comey’s third option on Oct. 27? Wait and see. Monitor the progress of the review closely. Do nothing until there was something to report.