The FBI believes that Hillary Clinton was "extremely careless" in her use of a private email account while secretary of state but that she should not be prosecuted for it, agency director James Comey announced at a press conference moments ago. The FBI was investigating whether Clinton had mishandled classified material in an intentional or criminally negligent manner when she set up a private account rather than using a State Department email address during her 2009–13 tenure as secretary; its recommendations are now in the hands of Justice Department officials. (Here's a transcript of Comey's remarks.) Attorney general Loretta Lynch said in the wake of her controversial meeting with Bill Clinton last week that she will accept her department's decision on the matter without exerting any influence.
In his statement, Comey said that the FBI's investigation had found 110 emails on Clinton's servers that had contained classified information when they were sent or received, of which eight contained material at the highest classification level of "top secret." Noting that this information was being stored on "unclassified personal servers" less secure even than commercial services like Gmail and that Clinton's use of the private account was widely known, Comey said it was "possible that hostile actors gained access to Secretary Clinton's personal email account." (There is no "direct evidence" of a hack.) Said Comey: "Any reasonable person should have known that an unclassified system was no place for that kind of information."
While Comey said the FBI had found evidence of "potential violations" of federal law, which allows prosecutions involving negligence, he concluded that "our judgment is that no reasonable prosecutor would bring such a case" and that "no charges are appropriate" because of the lack of precedent for prosecutions of such relatively minor violations. Said Comey: "We cannot find a case that would support bringing criminal charges on these facts." The FBI, Comey elaborated, had found no example of a prior prosecution ever having been brought in a classified-information case that did not involve intentional mishandling of material, "vast quantities" of mishandled information, evidence of disloyalty to the United States, or efforts to obstruct justice.
Comey also said that investigators had used forensic analysis to uncover "several thousand" work-related emails that were not among the group Clinton turned over to the State Department for recordkeeping purposes in 2014; however, he said, there is no evidence that those emails were hidden intentionally rather than simply having been deleted in the normal course of business or simply missed when her lawyers were sorting her emails into work and personal files.
This post has been updated with additional information.