Once the House committee votes in favor of citing Attorney General Eric Holder in contempt, it goes to the full House for consideration.
If the full House votes in favor of the contempt citation, the issue is sent to the U.S. attorney for the District of Columbia. A federal law adopted by Congress in 1857 directs federal prosecutors to refer these matters to a grand jury for possible prosecution. The language is mandatory as to the U.S. attorney: "whose duty it shall be to bring the matter before the grand jury for its action."
But from there on, it gets complicated.
The Justice Department has long taken the position, as a separation of powers matter, that Congress cannot force the Justice Department to undertake a prosecution of an executive branch official. The courts have never resolved the question.
The Justice Department, under both Democratic and Republican administrations, has further claimed that a U.S. attorney must not initiate a prosecution when the president has asserted executive privilege over what Congress seeks.
The administration of George W. Bush most recently made this claim during the congressional investigation of the firings of several U.S. attorneys nationwide. Congress subpoenaed former White House counsel Harriet Miers and Chief of Staff Josh Bolton, and the president directed that neither should testify or produce the requested documents. Though the broad issue of executive privlege went to court, it is still unresolved.
Another gray area here is how much a president can cover under the umbrella of an assertion of executive privilege. The further a matter gets from the White House and presidential decision making, the more the courts have been unwilling to recognize it.
On a broader point, the federal courts have been reluctant to referee what they see as fights between the White House and Congress. During the legal battle over Miers, the federal district court in Washington practically begged the two sides to work it out without suing each other.
"The court strongly encourages the political branches to resume their discourse and negotiations in an effort to resolve their differences constructively," it said.
And finally, there's this point to remember: if this does end up in court, it could take up to two years to resolve, given the time for a trial and subsequent appeals. However, a contempt citation is valid only during the Congress which approved it. Each term of Congress lasts only two years, so if the issue was still in the courts when this Congress ends in a year and a half, the contempt citation would evaporate, and so would any lawsuit.