What Is Gerrymandering? Supreme Court to Hear Potentially Landmark Case

Chief Justice of the United States John Roberts (right) and Associate Justice Neil Gorsuch are joined by Louise Gorsuch during Gorsuch's investiture ceremony at the Supreme Court in Washington, D.C., on June 15. The court announced Monday that it will consider a partisan gerrymandering case from Wisconsin. REUTERS/Joshua Roberts

The Supreme Court announced Monday it will consider if politically gerrymandered electoral maps in Wisconsin are unconstitutional, which could have a major impact on U.S. elections.

The court has already ruled against state electoral maps due to racial gerrymandering, but this could be the first case in which it decides just how much partisan gerrymandering is too much. The court will examine a case from Wisconsin in which a group of voters from across the state contend that Republican state legislatures acted unconstitutionally in drawing the map to benefit their party.

What is gerrymandering?

Gerrymandering is the practice of drawing electoral maps to benefit one's own political party. Although nonpartisan commissions control the drafting of these districts in a handful of states, partisan state legislatures in most states control the process. Redistricting occurs based on the results of the U.S. Census, which is held every 10 years. Political parties often use gerrymandering to manipulate district borders to increase their party's share of the vote. Racial gerrymandering, whereby the minority vote is intentionally diffused, has earned the attention of the Supreme Court in the past.

Lawmakers often take areas with a high percentage of voters for the opposing party and slice them up to be a small part of other districts that are more favorable to their party. Or they pack those areas into one congressional seat, conceding a seat but ensuring that fewer voters of the opposing party are in districts they can win.

Where did the term "gerrymandering" originate?

The word "Gerry-Mander" is more than 200 years old, with the Boston Gazette publishing the term in 1812 to describe then-Massachusetts governor Elbridge Gerry's attempt to manipulate the state's map to benefit his party.

How does racial gerrymandering work?

Many states had limited the electoral power of racial minorities by spreading them across a number of districts to prevent the population from being numerous enough in each district to have a significant effect. The 1965 Voting Rights Act outlawed that practice by requiring states to create "majority-minority" districts, which are districts featuring a majority of voters from a single minority group. While those districts have allowed minorities to pick their representatives, they have had the unintended consequence of limiting minority influence in other districts by packing them into one.

Which party currently benefits the most from gerrymandering?

The Republican party currently controls a majority of state legislatures and, thus, re-districting in most states. Republicans control 32 state legislatures, while Democrats control just 12 (six are split). The Republican National Committee and 12 Republican states have asked the Supreme Court to reverse the lower court's decision that the Wisconsin electoral map was an unconstitutionally partisan gerrymander.

Has the Supreme Court decided gerrymandering cases in the past?

The Supreme Court has taken a look at a number of gerrymandering cases over the years. It has been willing to take a position on racial gerrymandering, including in May, when it upheld a decision ruling that two North Carolina congressional districts were racial gerrymanders. The last time the court examined a partisan gerrymander case was in 2004, when the court could not agree on a way to test when political gerrymandering becomes an unconstitutional dilution of another's vote, as The Washington Post explained.

Why is the Supreme Court looking at Wisconsin?

A divided group of three federal judges determined in 2016 that Wisconsin Republicans violated the First Amendment and the Constitution's Equal Protection Clause with their 2011 redistricting. The court is now considering this case, Gill v. Whitford, on appeal. In 2012, the first election following the enactment of the new maps, Republicans received only 48.6 percent of the vote but won a 60-to-39 legislative advantage in the State Assembly.

What effect may this case have?

This case could have "enormous ramifications," Steve Vladeck, a professor of law at the University of Texas School of Law, told CNN. This would be the first time the court has "articulated a constitutional rule in this context," he said.

"Although a majority of the court has suggested that states can violate the Constitution if they draw legislative districts primarily to benefit one political party, the justices have never been able to identify the specific point at which states cross the constitutional line," Vladeck explained. "In this case, a lower court held that Wisconsin had indeed crossed that line."

Josh Douglas, a law professor at the University of Kentucky College of Law, toldCNN the case "will be the biggest and most important election law case in decades."