Republicans in Congress grilled FBI Director James Comey for more than four and a half hours Thursday over his decision not to recommend criminal charges against Hillary Clinton over her use of a private email server while secretary of state.
"We believe that you have set a precedent, and it's a dangerous one ... that there's going to be no consequence," said Congressmman Jason Chaffetz, who leads the House of Representatives' government oversight panel.
Comey this week said an FBI investigation about Clinton's email and the handling of classified information had shown she and her staff were careless but had not intended to commit a crime.
The issue has dogged Clinton's presidential campaign, and Republicans were outraged that Clinton was cleared despite apparently mishandling classified material.
Comey told Congress that the FBI had acted in "an apolitical and professional way, including in our recommendation."
No reasonable prosecutor would bring a case against Clinton, he said, noting that a law against acting with gross negligence with classified material has very rarely been used to prosecute anyone.
There was no evidence Clinton had lied to the FBI, and Comey said he was not in a position to say whether she had lied to the public about her email.
Comey said he could understand the inquiry, even as Democrats on the committee dismissed the hearing as "political theatre."
"I totally I get people's questions, and I think they're in good faith," he said.
Clinton's campaign expressed satisfaction that the hearing had cleared up some of the concerns about the FBI's decision, saying it "shut the door on any remaining conspiracy theories once and for all."
"Despite the partisan motivations of this hearing, we are glad it took place and that Director Comey had the opportunity to expand upon his remarks from earlier this week," campaign spokesman Brian Fallon said.
The testimony "clearly knocked down a number of false Republican talking points and reconciled apparent contradictions between his previous remarks and Hillary Clinton's public statements."
Later Thursday, the State Department told several media outlets that it was resuming an administrative probe of the Clinton email case, which had been halted to avoid conflicts with the FBI's criminal investigation. The internal investigation could lead to disciplinary action against current State Department employees, and could affect the security clearances still held by former staff, spokesman John Kirby said.
Chaffetz and other Republicans grilled Comey about what consequences there would have been for an FBI employee who handled classified material as carelessly as Clinton.
Questions centred around whether classified information sent on Clinton's email had been clearly marked as classified, and Comey said some of the material had not been properly marked.
Concerns about Clinton's email use prompted House Speaker Paul Ryan, the top Republican in Congress, to call for her to be denied access to classified intelligence briefings traditionally given to presidential candidates in order to prepare them should they be elected.
Attorney General Loretta Lynch said Wednesday that she would follow the recommendation of the FBI and prosecutors and bring no charges against Clinton.
Clinton's presidential campaign had been under a cloud due to the investigation of her use of a private server for all her work-related email. Wednesday's announcement lifted the threat of prosecution, a day after Comey painted a picture of sloppiness that could continue to haunt her campaign.
A State Department review released in May faulted Clinton's exclusive use of the private email server as secretary of state from 2009-13, saying the practice posed a security risk and did not comply with government records laws.
Republicans have cited the issue to impugn Clinton's trustworthiness and judgement as she runs for president and to raise the spectre of the scandals that plagued her husband Bill Clinton's 1993-2001 presidency.