The Supreme Court has just heard oral argument in the highly anticipated case of Gill v. Whitford on the constitutionality of political gerrymandering. At issue is Wisconsin’s Act 43, a state redistricting plan enacted by a Republican legislature in 2011, which allowed the GOP to capture both houses of the state legislature in the 2012 and 2014 elections by turning a Republican vote of under 50 percent into a near 60 percent majority in legislative seats. But the act was then successfully challenged in federal district court before Wisconsin appealed to the Supreme Court.

In the case, the GOP relied on the familiar technique of partisan gerrymandering, long used by both parties, to fashion districts that force the opposition to “waste” its votes. The opposition racks up huge majorities in a small number of districts, enabling the controlling party to gain a larger number of seats by smaller majorities. One measure of the effectiveness of this technique is the much debated “efficiency gap.” As the challengers explain in their brief, that is “calculated by taking one party’s total wasted votes in an election, subtracting the other party’s total wasted votes, and dividing by the total number of votes cast.” The greater the gap, the greater the imbalance of wasted votes between parties—and the more likely that the gerrymandering will give the controlling party influence greater than its share of the statewide popular vote.

The Justices agreed in oral argument that this bipartisan practice is deeply unsavory. But then disagreement quickly set in about whether any possible cure would be worse than the disease itself, as Wisconsin stoutly insisted in its brief that decried the want of predictable remedial standards. Let a challenge succeed in one state, and similar challenges will be raised everywhere. Given the interdependence of district boundaries, changing one district could necessitate redrawing a state’s entire map.