In a surprise 15-minute press conference on Tuesday, Federal Bureau of Investigation Director James Comey issued a harsh assessment of former Secretary of State Hillary Clinton’s use of a private e-mail server, calling her handling of classified data “extremely careless” and suggesting that it was possible her home-based mail server had been breached by hackers.

But Comey said he would recommend no criminal charges be filed against Clinton, citing that there was a lack of evidence that Clinton had intended to expose or transmit classified data, or that she mishandled information in a willful oversight of her responsibilities. That decision has already drawn calls from Republicans for an independent investigation.

Comey’s conclusion was that no reasonable prosecutor would try to make a case out of the evidence collected in the investigation. Though the Justice Department has certainly done so with other cases of mishandling classified data, those cases have involved more willful acting, and anything not directly involving espionage generally results in relatively light punishment.