Science and Culture: Math tools send legislators back to the drawing board [Political Sciences]

*UPDATE: On June 18, 2018, after this article went to press, the Supreme Court of the United States ruled on two high-profile cases related to partisan gerrymandering. In effect, the rulings sidestepped the issue of when partisan gerrymandering is unconstitutional. Both cases—one concerning voting districts in Wisconsin, the other in Maryland—were sent back to lower courts. On June 25, the SCOTUS ruled on two other cases—in Texas and North Carolina—that will mostly let stand the use of purportedly gerrymandered maps. On January 9, 2018, a trio of federal judges made history when they ruled that the boundaries of North Carolina’s congressional voting districts gave an unfair advantage to Republican candidates. It was the first case in the nation in which a federal court had declared congressional maps unconstitutional because of intentional bias in favor of one party. The case was all the more remarkable because the court decision relied in part on mathematical tools that can probe the practice of gerrymandering—the drawing of voting districts to give an intentional advantage to one party. Changing the boundaries of voting districts can have a significant impact on an election outcome. North Carolina’s 2012 election districting map (bottom) led to Republicans winning nine seats and Democrats winning four. North Carolina’s redistricting for the 2016 election (middle map) led to Republicans winning 10 seats and Democrats winning three seats. But an arguably fairer redistricting plan (top), produced by retired judges, would have led to Republicans winning seven seats and Democrats the other six in 2012; it would have been nine seats for Republicans and four for Democrats in 2016. Image courtesy of Jonathan Mattingly (Duke University, Durham, NC). It would be one of many gerrymandering cases. In February, the US Supreme Court rejected a request by Republican lawmakers to stay a lower court's decision—which …