Comey began his address by explaining what investigators found during their investigation. He said that the investigation showed that 110 emails in 52 email chains were determined to include classified information at the time they were received.
Comey also said the FBI assessed that there was no direct evidence that Clinton's personal email domain was hacked. It is possible, however, that hostile actors gained access, he added.
He characterized the investigation findings as showing that Clinton and her team were "extremely careless" but he said there was no clear evidence they intended to violate the law.
Still, Comey said the FBI's recommendation is that Clinton no face criminal charges for her actions.
"Our judgment is that no reasonable prosecutor would bring such a case," he said.