FBI Director James Comey faced skeptical and angry congressional Republicans this morning in a hastily called hearing on Capitol Hill to question his findings in the probe into Hillary Clinton's use of a private email server.

In his opening statement, the chairman of the House Oversight and Government Reform Committee, Jason Chaffetz, R-Utah, accused Comey of setting a "dangerous" precedent that will allow officials to "sloppily" handle classified information with "no consequence."

Chaffetz said Comey's determination that charges weren't warranted in the case sent a message that "if your name isn't Clinton or you aren't part of the powerful elite ... Lady Justice will act differently" toward you.

But Comey strongly defended his recommendation that charges not be brought against Clinton or her aides for mishandling classified information by using a private email server when she was secretary of state.

"The decision was made and the recommendation was made the way you would want it to be, by people who didn't give a hoot about politics but who cared about what are the facts, what is the law and how have similar people -— all people —- been treated in the past," he told the House panel.

In explaining his decision, Comey said two things matter in a criminal probe: "What did the person do ... and when they did it, did they know they were doing something that was unlawful?"

"That is the characteristic of all prosecutions of mishandling classified information," he added.

And while there is a federal law dealing with "gross negligence," Comey said that does not mean prosecutors shouldn't consider the mindset of a subject when deciding whether to bring charges, by "American tradition."

He said that because of "grave concerns" over use of the gross negligence law, it has been used by federal prosecutors only once in its 99-year history, and that case involved espionage.

"When I look at the facts we gathered here, as I said, I see evidence of great carelessness, but I do not see evidence sufficient to establish that Secretary Clinton or those with whom she was corresponding both talked about classified information on email and knew when they did it that they were doing something that was against the law," Comey said today. "No reasonable prosecutor would bring this case ... Nobody would. Nobody did."

He called the FBI probe "apolitical," "competent, honest and independent."

Nevertheless, Chaffetz told Comey he and others were "mystified" and "confused" by the FBI's findings and recommendation.

"It seems that there are two standards, and there's no consequence for these types of activities and dealing in a careless way with classified information," he said.

In his opening remarks, the top Democrat on the panel, Rep. Elijah Cummings, D-Md., insisted the Republican backlash was rooted in anger that Comey's findings "conflicted with the predetermined outcome they wanted."

"In their eyes, you had one job, and one job only: to prosecute Hillary Clinton," Cummings told Comey. "In a sense, Mr. Director, you're on trial."

Cummings condemned the subsequent attacks on Comey, particularly personal attacks and conspiracy theories that have been spun, including one suggesting senior law enforcement officials may have bribed.

When announcing his findings Tuesday, Comey harshly criticized Clinton and her State Department team for being “extremely careless in their handling of very sensitive, highly classified information. But he said the FBI recommended against charging Clinton or her aides criminally.

The decision set off a firestorm of criticism from Republicans and prompted a quick call for congressional hearings.

"The FBI's recommendation is surprising and confusing," Chaffetz said in a statement announcing today's hearing. "The fact pattern presented by Director Comey makes clear Secretary Clinton violated the law. Individuals who intentionally skirt the law must be held accountable."

Speaker of the House Paul Ryan said the decision looked like "preferential treatment for Clinton.”

Here are some key areas and questions covered by Comey today:

WHAT IS THE LEGAL STANDARD INVOLVED HERE?

Comey said that when looking at allegations of mishandling classified information, two things matter: “What did the person do… and when they did it, did they know they were doing something that was unlawful.”

Asked specifically whether Clinton broke the law, Comey said: “My judgment is she did not. … The question I always look at is, is there evidence that would establish beyond a reasonable doubt that somebody engaged in conduct that violated a criminal statute. And my judgment here is there is not.”

Comey said “the challenge” is that U.S. law is reserved “for people who clearly knew they were breaking the law.”

“So ‘should have known,’ ‘must have known,’ ‘had to know’ does not get you there. You must prove beyond a reasonable doubt that they knew they were engaged in something that was unlawful.”

WHAT ABOUT CHARGING CLINTON WITH “GROSS NEGLIGENCE”?

There is a U.S. law that makes mishandling classified information through “gross negligence” – rather than intent – a crime. But Comey said the Justice Department – through Republican and Democratic administrations – have long had “grave concerns” that the law may actually be unconstitutional, so federal prosecutors have been reluctant to use the law. In fact, in the law’s 99 years on the books, prosecutors have only charges someone once, and that involved espionage, according to Comey.

“There’s no way anybody at the Department of Justice is bringing a case against John Doe or Hillary Clinton for the second time in 100 years based on [the] facts” of this case, Comey insisted.

To the former prosecutors and “friends” who claim they would have brought charges in this case, Comey asked with a chuckle: “So where were you over the last 40 years? Where were these cases? They just have not been brought for … It’s a good thing that the Department of Justice worries about prosecuting people for being careless. … As a citizen, I want people to show they knew they were breaking the law, and then we’ll put you in jail.”

When it comes to Clinton, “certainly she should have known not to send classified information,” and, “that’s the definition of negligent,” Comey said.

“I think she was extremely careless, I think she was negligent. That I could establish,” he added. “What we cant establish is that she acted with the necessary criminal intent.”

ISN’T THIS CASE LIKE THE ONE MADE AGAINST GEN. DAVID PETRAEUS?

Comey dismissed any comparisons between the Clinton case and the prosecution of Gen. David Petraeus, who ultimately pleaded guilty to a misdemeanor for sharing classified information with his mistress, who was writing a book about him. Unlike Clinton, Petraeus kept “vast quantities” of what he knew was highly classified information in eight personal notebooks hidden in his home, gave that info to his mistress, and lied about it all to the FBI, in effect obstructing justice, Comey said. So what Petraeus did was “clearly intentional” and far worse, and the precisely the kind of case that warrants prosecution, according to Comey.

WHO TOOK PART IN THE INVESTIGATION?

Comey said a team of 15-20 agent investigated the case, with help at times from other FBI personnel. He said the investigators and prosecutors involved “didn’t give a hoot about politics,” only “about what are the facts, what is the law and how have similar people – all people – been treated in the past.” He called them all “an all-star team.”

WAS CLINTON’S PERSONAL EMAIL SERVER HACKED?

Comey said that while there’s no information to indicate adversaries successfully hacked Clinton’s personal email server, “it’s possible” that did happen. However, Comey refuted public claims by one prominent hacker, known as “Guccifer,” that he was able to break into Clinton’s server.

“He did not, he admitted that was a lie,” Comey said today.