America’s anti-gerrymandering law is an incoherent mess.

Thirty years ago, in Davis v. Bandemer, the Supreme Court held that a partisan gerrymander may be struck down as unconstitutional upon proof of “both intentional discrimination against an identifiable political group and an actual discriminatory effect on that group.” Yet the Court struggled to determine where to draw the line between lawful and unlawful maps.

Nearly two decades later, in Vieth v. Jubelirer, the justices seemed even more confused. Four of them called upon federal courts to simply give up on solving the problem of partisan gerrymanders. Four others splintered into a maze of dissenting opinions, altogether proposing a total of three different standards for weighing alleged gerrymanders. In the middle, Justice Anthony Kennedy threw up his hands in frustration. “The failings of the many proposed standards for measuring the burden a gerrymander imposes on representational rights make our intervention improper,” Kennedy wrote. Nevertheless, he concluded that “if workable standards do emerge to measure these burdens . . . courts should be prepared to order relief.”

Now, a dozen years after Kennedy despaired for want of a workable way to uncover partisan gerrymanders, two young scholars may have cracked the code. In a paper published in the University of Chicago Law Review last year, law professor Nicholas Stephanopoulos and political scientist Eric McGhee propose a mathematical formula judges can use to identify suspect maps. This formula is now the subject of a federal lawsuit, Whitford v. Nichol, which has survived two motions, submitted by defenders of Wisconsin’s Republican-drawn maps, that sought to kill the case. Moreover, because of a quirk of federal law, the case is overwhelmingly likely to wind up in the Supreme Court.

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