That means the Supreme Court is very likely to weigh in on the fate of political gerrymandering, probably during the court’s next term, which starts in October.

There are two basic ways to inject partisan politics into drawing legislative maps: packing and cracking. Both result in what Nicholas O. Stephanopoulos, a law professor at the University of Chicago and a lawyer for the plaintiffs, calls “wasted votes.”

Packing a lot of Democrats into a single district, for instance, wastes every Democratic vote beyond the bare majority needed to elect a Democratic candidate. Cracking Democratic voters across districts in which Republicans have small majorities wastes all of the Democratic votes when the Republican candidate wins.

In an influential article, Professor Stephanopoulos and his colleague Eric McGhee applied a little math to this observation. The difference between the two parties’ wasted votes, divided by the total number of votes cast, yields an efficiency gap, they wrote. In a world of perfect nonpartisanship, there would be no gap.

The gap in Wisconsin was 13.3 percent in 2012 and 9.6 percent in 2014.

The Wisconsin voters who sued to challenge the Assembly map argued that gaps over 7 percent violate the Constitution. That number was meant to capture the likelihood that the gap would endure over a 10-year election cycle, but critics say it is arbitrary.

Adopting it, they say, would transform American elections. A 2015 report from Simon Jackman, then a political scientist at Stanford and an expert witness for the plaintiffs, found that a third of all redistricting plans in 41 states over a 43-year period failed the 7 percent standard. Elections in 2012 and 2014 in Florida, Indiana, Kansas, Michigan, Missouri, North Carolina, New York, Ohio, Rhode Island, Virginia, Wisconsin and Wyoming featured efficiency gaps of more than 10 percent, Professor Jackman found.