In the House of Representatives, the majority party holds most of the cards. It gets to write the chamber's rules, it has the votes to pick the speaker of the House, it decides which bills come to the floor (and which ones don't), and it determines how those bills are debated. That's why it's often a frustrating and demoralizing ordeal for a representative to be stuck in the minority.

As I document in my recent book, however, the majority doesn't possess the entire deck. In fact, the minority party in the House has repeatedly, and often significantly, exercised influence. Policies as broad-reaching as the BRAC process for closing military bases to practices as minor as the House's daily recitation of the Pledge of Allegiance owe their authorship to members of the minority party.

This past year in particular, the House's Democratic minority has exerted itself quite effectively. In June, Democrats temporarily derailed a measure to create a "fast track" process for approving trade agreements. A month later, Republicans pulled the Interior-EPA spending bill from the House floor after Democrats vociferously objected to an effort to undo a newly added ban on the Confederate flag at federal cemeteries. More recently, Minority Leader Nancy Pelosi assiduously built a big enough coalition of Democrats in favor of the Iran nuclear agreement that Republicans would be unable to override a veto against a resolution disapproving the agreement. The GOP instead reverted to an elaborate "triple-vote" tactic that was largely symbolic.

There are two major reasons the House minority party has been sitting pretty since the 2014 elections. First, Democrats are more unified than Republicans. That matters because if Republican leaders can't get enough of their troops in line to pass bills, those bills fail without Democratic votes. And that gives the minority party leverage.

Look, for instance, at aggregate voting patterns. Since 1995, the majority party in the House has always had a higher voting unity score than the minority. (A party's voting unity score is the average percentage of the time its members cast their ballots with their party whenever the two parties are on opposite sides of a vote.) But in recent years, the scores of minority party Democrats have been climbing. In fact, as of mid-September the Democrats' score for 2015 was actually a smidgeon greater than the Republicans' (91.9 percent versus 91.8 percent).

But party unity scores conceal the deeper divisions within the Republican Party. The GOP's biggest dissenters have organized into the House Freedom Caucus (HFC), which has enough members (40 or so) to combine with a unified minority party to kill Republican bills they deem insufficiently conservative. That they are organized is critical: Though HFC members tend to be more conservative than their House colleagues, their average party unity score to date is actually higher (92.6 percent) than the GOP average. However, when they oppose bills as a bloc, the HFC represents a pivotal faction that can defeat those bills if Democrats vote against them too. This constrains the majority party's power to set the legislative agenda, as Rep. Tom McClintock (R-CA) pointed out in his letter of resignation from the HFC on September 16.

House Democrats have been in an advantageous position this year because their party has less to lose should Congress fail to legislate

Now, with a government shutdown looming, the HFC has flexed its muscles, insisting that its members will not vote for any spending bill that fails to defund Planned Parenthood. Coupled with the threat from a handful of conservatives to remove Boehner as speaker (however unlikely that may be), this move puts significant pressure on Boehner to pass a spending bill the HFC wants, even if it will almost certainly be vetoed by Obama or blocked in the Senate. Boehner's alternative is to turn to the minority party, which has insisted it won't vote for any bill to fund the government unless Republicans agree to negotiate an increase in nonmilitary as well as military spending.

The other reason House Democrats have been in an advantageous position this year, and are in one now, is that their party has less to lose should Congress fail to legislate. Obama is a lame duck president, so he doesn't have to face voters who would be upset by a government shutdown. It also means House Democrats are less worried that their actions might hurt the president politically, as evidenced by their earlier willingness to buck Obama and vote against the trade bill the president wanted.

Meanwhile, because Democrats lost their majority in the Senate last November, it is more likely to be Senate Republicans, not Democrats, who are blamed for bad outcomes like a government shutdown. Thus Pelosi feels no pressure to protect the party's majority in the Senate (as she did two years ago, during the last shutdown) and has more leeway in pushing for tough demands in negotiations with the GOP.

It's not certain, of course, that House Democrats will be able to use their political leverage in the current showdown over government funding. If, for instance, there is a lengthy and painful shutdown, the party may eventually feel enough political pressure from constituents and others to vote for an appropriations bill with less domestic spending than they've demanded. And the power of House Democrats is augmented significantly by cooperation from Senate Democrats and the White House. Though Obama, Reid, and Pelosi stand together for now in demanding more spending in whatever funding bill comes from Congress, there's no guarantee that cooperation will continue. In fact, one longtime budget expert doesn't think congressional Democrats will be a part of negotiations over government spending at all.

Nonetheless, the circumstances throughout this year have been quite favorable to House Democrats. It's a reminder that no matter how majoritarian the House of Representatives may be, there is always the chance that the minority may matter.

Matthew Green is an associate professor of politics at the Catholic University of America in Washington, DC. His book Underdog Politics: The Minority Party in the U.S. House of Representatives was published in January by Yale University Press.