by Dan Froomkin
Federal prosecutors – even those not working on cases of major public interest – may well uncover facts in the course of their investigations that if made public would have explosive political ramifications.
But Justice Department rules are extraordinarily strict: Neither prosecutors nor the FBI can tell anyone what they've discovered unless it's in the fulfillment of their official duties.
That's important: the process of investigation often turns up things that are not true, or do not amount to crimes, but that could nevertheless ruin reputations. (The November 2017 update of the U.S. Attorney's Manual includes new language about the "General Need for Confidentiality" that is different, but consistent, with the previous version.)