In short: We don't know yet. But it's also quite possible that nobody will ever be convicted of breaking the law in the IRS scandal.
"I am not aware of any statute that prohibits IRS targeting of applicants," said Republican lawyer Jan Baran, who served as general counsel to George H.W. Bush and the RNC. Other politically inclined lawyers agree.
Essentially, there are three types of laws that might conceivably have been broken, as Attorney General Eric Holder acknowledged in his testimony before a House committee Wednesday:
1) Civil rights laws that protect people from being discriminated against by the government
2) The Hatch Act, which prevents civil servants from engaging in partisan political activity
3) Perjury laws, which prevent people from lying to Congress
For the third law to have been broken, Republicans would have to prove that IRS officials knew of improper targeting of conservatives and testified to the opposite effect. They have noted that then-IRS commissioner Douglas Shulman testified in March 2012 that there was no such targeting going on.
But for that to be perjury, Shulman would have had to know that he was lying. Miller admitted Friday that Shulman was wrong but suggested he wasn't aware of the targeting.
"It was incorrect, but whether it was untruthful or not ... " Miller said, tailing off. He later added: "To my knowledge, I don't believe he knew at the time."
As for the first two laws, it likely would have to be proved that the staff members involved in targeting the conservative groups were deliberately doing so for political purposes.
“You would want some direct evidence of intent, that people knew what they were doing was wrong and they decided to do it anyway,” Nathan Hochman, a former assistant attorney general in the Justice Department's tax division, told Bloomberg News.
Miller and other top IRS officials contend that's not the case, and that it's simply happenstance that conservative-sounding organizations were prominent among those who were inappropriately singled out.
(Side note: Despite making this point, the IRS officials haven't done a good job of explaining exactly how these conservative groups were targeted — and liberal ones weren't — if it wasn't political.)
It may seem self-evident that the motivation was political, but proving that in a court of law is another matter entirely. And until that political motivation is proven, it will be tough to land convictions under the first two laws mentioned above.
That's also why we're seeing such a concerted effort from the IRS to emphasize that it was about incompetence rather than politics.
Apart from what's mentioned above, you could make a case that the IRS's targeting of conservative groups violates the Constitution. The 1st Amendment could have been violated if the extra scrutiny is deemed to have hindered these groups' freedom of speech; the 14th Amendment could come into play if the practice violated the equal protection clause, which prevents the government from discriminating against its people; and the 4th Amendment's could be applied if the scrutiny is seen as "unreasonable search and seizure."
But violating the Constitution isn't technically a crime.
"It is possible for a taxpayer to sue individual employees for allegedly denying them constitutional rights. This usually arises in the context of searches or seizures in violation of the 4th Amendment," Baran said. "In any case, such suits are private civil suits, not criminal suits, and are very difficult to succeed in."
And in fact, the inspector general responsible for investigating the IRS, Russell George, agreed with Miller that no laws were broken when the conservative groups were targeted.
"It is not illegal, sir, but it was unusual," George said.
Which means that, in the end, it's quite possible nobody will go to jail for what happened at the IRS.