Redistricting Explainer: Everything you need to know about gerrymandering and the case before the Supreme Court

Congressional Districts, Clockwise from top left: NC 12, FL 5, PA 7, TX 33, NC 1, MD 3. Image: NBC News

For the first time in over a decade, the Supreme Court will consider whether partisan gerrymandering is constitutional. The court will hear an appeal of a District Court case that struck down Wisconsin’s State Assembly map as illegally gerrymandered last year.

Judge Kenneth Ripple, writing for the majority, noted that the map deliberately made it “more difficult for Democrats, compared to Republicans, to translate their votes into seats.” The Supreme Court’s choice to uphold or overrule the District Court’s decision could have a wide-ranging impact on redistricting across the country.

What is gerrymandering and how is it done?

District maps for U.S. Congress and state legislatures are redrawn every ten years following the Census to reflect changes in state populations. Usually, this is done by state legislatures, but not always — you can check your state’s process here. In certain instances, these lines have been drawn with the hopes of giving one political party an advantage in future elections.

Districts can be made favorable to a certain party, or gerrymandered, by maximizing the number of “wasted” votes for the opposition party. These include any votes cast for a losing candidate or any vote cast for a winning one beyond their victory threshold. There are two common techniques of gerrymandering: cracking and packing. When cracking, voters of the opposition party are spread among several districts, losing each district narrowly but winning none. Packing fills a district with opposition votes, wasting all the extra votes beyond what was needed to win. This often results in wildly shaped districts stretching across much of a state, sometimes as slim as one house thick.

Gerrymandering is at least as old as the first Congress, when Patrick Henry attempted, unsuccessfully, to keep his political enemy James Madison out of office.The word gerrymandering came about, later, in 1812, when Massachusetts Governor Elbridge Gerry helped create a salamander-shaped district to help secure a seat for his party.

So far, the Supreme Court has only ruled against gerrymandering designed to hurt or help members of a certain race, while allowing partisan gerrymandering to stand. Most recently, in the 2004 case Vieth v. Jubelirer, a 5–4 majority upheld the constitutionality of partisan gerrymandering. Justice Anthony Kennedy, in his concurring opinion, argued that if there were “working standard” to determine the constitutionality of the issue, he would consider a fresh challenge to the process.

Gill v. Whitford and its Impact

The current Wisconsin State Assembly map, drawn by a Republican-controlled legislature in 2011, saw close vote margins for the state assembly produce large majorities for Wisconsin Republicans. A group of concerned voters, led by retired law professor William Whitford, a longtime Democratic activist, filed a suit arguing this was the result of illegal gerrymandering. They cited the recently-developed “efficiency gap,” which measures the difference in wasted votes between the two parties, as a percent of total votes. Since cracking and packing are designed to waste one party’s votes, the plaintiffs argue the gap can reveal partisan gerrymandering. Wisconsin’s efficiency gap is one of the nation’s highest.

The state of Wisconsin, supported by the RNC and twelve other states, argues that the disparity in election results, and the high efficiency gap, is a result of geographic sorting, not gerrymandering. Democratic voters tend to be highly concentrated around urban areas, wasting more of their votes, compared to the more spread-out Republican voters. The District Court credited some of the Republican advantage in Wisconsin’s state assembly map to this geographic sorting, but ruled the rest the result of partisan gerrymandering, which thus violated the Free Speech and Equal Protection Clauses of the Constitution.

The state appealed the ruling to the Supreme Court. The decision will likely hinge on Justice Kennedy once again as he decides whether the efficiency gap meets the “workable standard” he sought out in 2004. Oral arguments in Gill v. Whitford are scheduled for October.

The decision could ripple far beyond the Badger State. A ruling in favor of the plaintiffs could invalidate other districts around the country. If any states are forced to redraw their districts, competition at the state and national level is bound to increase, as cracking and packing become less common throughout the country. For over 200 years, some politicians have drawn districts to help their own parties. They soon may find it much harder to do.

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By Michael Lynch, BallotReady Intern