What’s going to happen in North Carolina’s 9th Congressional District? That’s a question currently without an answer. Republican Mark Harris was initially declared the winner, but after allegations of election fraud cast doubt on the integrity of the vote, the next steps remain uncertain. With The Washington Post now reporting that Harris personally directed the hiring of the operative at the center of the potential fraud — even after being warned of his suspect methods — it’s entirely possible that the state board of elections could order a brand new election.

Or, the new Democratic-controlled House could get involved. Article I, Section 5 of the U.S. Constitution states that each chamber of Congress “shall be the Judge of the Elections, Returns and Qualifications of its own Members.” What this means in the North Carolina race is that the House has ultimate authority to decide disputed House elections. The House could play a part if the losing candidate, Democrat Dan McCready, files a contest under the Federal Contested Elections Act of 1969, or if the House refers the matter to its Administration Committee for an investigation.

They’re far less common nowadays, but the House has a long history with contested elections. In fact, the first case dates back to the 1st Congress in 1789. According to a 2018 study by Jeffery Jenkins, a professor of public policy and political science at the University of Southern California, and Charles Stewart, a professor of political science at the Massachusetts Institute of Technology, results in 594 House seats were contested from 1789 to 2012. Jenkins and Stewart wanted to examine the role contested elections played as the House matured. What they found was that although the number of contested elections had decreased, votes by the House to decide contested elections remained partisan over time. That is, whatever the merits of the dispute, if a contested election came to a vote, GOP-controlled Houses generally sided with GOP candidates while Democratic Houses backed Democratic candidates.

Contested elections used to be more common Average share of U.S. House seats contested, by decade Decade Congress contested seats Avg. number of seats for Decade AVg. share of contested seats 1789–98 1–5 18 90 4.0 1799–1808 6–10 10 128 1.6 1809–18 11–15 14 167 1.7 1819–28 16–20 9 202 0.9 1829–38 21–25 11 230 1.0 1839–48 26–30 36 233 3.1 1849–58 31–35 14 234 1.2 1859–68 36–40 50 205 4.9 1869–78 41–45 75 273 5.5 1879–88 46–50 60 312 3.8 1889–98 51–55 85 347 4.9 1899–1908 56–60 34 375 1.8 1909–18 61–65 36 418 1.7 1919–28 66–70 29 435 1.3 1929–38 71–75 30 435 1.4 1939–48 76–80 17 435 0.8 1949–58 81–85 12 435 0.6 1959–68 86–90 15 436 0.7 1969–78 91–95 15 435 0.7 1979–88 96–100 9 435 0.4 1989–98 101–105 6 435 0.3 1999–2008 106–110 8 435 0.4 2009–12 111–112* 1 435 0.1 Data after the 112th Congress was not available. A contested election indicates a result that was formally disputed in the House. Not all contested races resulted in a different winner. The House reached its current size of 435 seats after the 1910 census, except for the 86th and 87th congresses (1959-1962), when it expanded to include at-large seats from Alaska and Hawaii. The House then returned to 435 seats after the 1960 census and the subsequent reapportionment before the 1962 election. Source: JEFFERY JENKINS, CHARLES STEWART

The largest share of contested elections came in the late 19th century, during and after Reconstruction, when disputes often arose over election results in the South. At that time, the GOP often used contested elections to counter the disenfranchisement of black voters and fraud perpetrated by Democrats in the South. Republicans sought to overturn results in order to expand narrow governing majorities during a highly competitive political era and to better maintain a foothold in the South. But after 1896, the GOP became more electorally dominant nationwide and no longer had as much partisan incentive to vigorously contest elections in the South. An average of 4.7 seats changed hands per Congress between 1869 and 1898 thanks to contested elections. Since then, there have been relatively few contested seats, and even fewer that led to a seat actually flipping when the House took up the case. In fact, in an earlier 2004 paper, Jenkins found only five instances after the 67th Congress (1921-1922) where the person disputing the election was declared the winner.

As for why an election result has historically been disputed, Jenkins identified a number of categories, but the leading cause was allegations of criminal action, including fraud, corruption and/or bribery. The second-most common justification was charges of election irregularities that were not criminal, including the participation of ineligible voters or the mishandling of ballot boxes. If North Carolina’s 9th District were to become a contested election, it would likely fit into one of those two categories, depending on the findings of a criminal probe investigating the activities of local GOP operative Leslie McCrae Dowless.

Whatever the justification, contesting an election used to be far more commonplace and seen as a valuable partisan tool — a means of adding seats to bolster thin margins for the majority party in the House. This doesn’t mean that it was easy to overturn results — in most cases, the original winner has won a disputed election in the House. But when a contested election has advanced to the House floor, the resulting vote has usually been along party lines, according to Jenkins and Stewart. During the late 19th Century, this sometimes meant significant gains for the majority party. In the 41st Congress (1869-70), for example, the GOP majority increased by 10 net seats(!) through overturned results.

But it’s been more than 30 years since a contested election reversed an outcome. The last time it happened was in 1985, when the Democratic-controlled House voted to seat Democratic Rep. Frank McCloskey after an investigation and recount conducted by the House Administration Committee found him ahead by just four votes. GOP members cried foul as the Republican candidate had previously led the race and there were still a handful of uncounted absentee votes. The Republicans staged a walkout in response and the entire episode is often cited as an inflection point in creating a more partisan and rancorous atmosphere in Washington.

Jenkins told FiveThirtyEight that he’s curious to see if contested elections become a renewed flash point in the country’s hyper-partisan environment. In their 2018 article, Jenkins and Stewart wrote that contested elections could once again emerge as a way for a political party to secure stronger governing majorities in an environment where neither party is dominant. In the partisan arms race, we’ve seen ever-more furious wrangling over things like Supreme Court confirmations. So it’s not hard to imagine contested elections becoming a new battlefield in Washington if the parties decide these disputes can help them shore up their governing majorities.