It's the first time in history the House of Representatives is voting to hold the highest-ranking American law official in contempt of Congress, and since Eric Holder's current predicament is so new and different, you're probably wondering what to expect. Here's our guide.

The allegedly contemptible: Attorney General Eric Holder

Why he's so contemptuous: The Department of Justice has handed over more than 7,000 documents related to the ATF's Fast and Furious operation, but the House Oversight Committee wants 1,500 more. Committee chair Darrell Issa alleges the operation allowed guns to be trafficked to Mexican cartels, that the guns were used to kill American border agent Brian Terry, and that the government made the operation flawed on purpose in order to advance the case for gun control. But as Fortune's Katherine Eban reported Wednesday, there's no evidence that the government ever intentionally allowed gangsters to get their hands on guns. And Issa has never made public the emails that he says show government officials thought the operation could make the case for gun control.

Will a majority vote to hold him in contempt? Probably. It's expected to be a mostly party-line vote, and Republicans have a majority.

How many Democrats will vote to hold him in contempt? Between four and 31. The Hill's Jordy Yager has four officially voting against Holder: Georgia's John Barrow, Minnesota's Collin Peterson, West Virginia's Nick Rahall, and Utah's Jim Matheson. But 31 Democrats sent a letter to Obama expressing concern over Fast and Furious last year. The National Rifle Association has made it clear that voting to hold Holder in contempt will be very important for legislators wanting to hang onto a good NRA rating.

Why is it on a Thursday afternoon? Republican leaders have been uncomfortable with the Fast and Furious investigation all year because they think it makes them look like they're not focused on the economy.

What time is the vote? The House will begin the process at about 12:30 p.m. ET, with the final contempt vote wrapping up by 5:30 p.m. ET, Fox News' Chad Pergram reports. They will vote first whether to hold him in criminal contempt and then whether to hold him in civil contempt.

What kind of theatrics can we expect? In addition to your typical angry speeches, the Congressional Black Caucus will walk out during the vote, Politico's Jonathan Allen reports.

And then what? Maybe nothing, CNN's Alan Silverleib reports. If the House holds Holder in criminal contempt, it would refer the case to District of Columbia U.S. Attorney Ronald Machen to determine whether to bring criminal charges against Holder, who, oh, by the way, is his boss. Last time something similar happened -- when House Democrats hold White House chief of staff Josh Bolten and counsel Harriet Miers in contempt in 2008 -- George W. Bush's Justice Department did nothing.

If the House votes for the civil action, Silverleib explains, then it can file a lawsuit demanding the Justice department documents as well as continue embarrassing the administration.