Aaron Goldzimer and I wrote this piece for Slate, arguing for a third-best response to congressional gerrymandering if neither Congress nor the federal courts are willing to tackle the problem. States should enact reforms requiring their congressional maps to be drawn to promote national partisan fairness to the extent possible. At present, if just a handful of key states did this (say California and New York alone), the result would be a nearly perfectly balanced House.

If existing state reforms are counterproductive, and if the federal government has consigned itself to the sidelines, how can a House that accurately reflects the will of the people be achieved? One promising idea is for blue states to require their congressional maps to promote national partisan fairness to the extent possible. There exist several statistical measures of maps’ partisan fairness. These metrics could be applied to the House as a whole rather than to any individual map. Blue states could then design their districts with the aim of minimizing the bias of the House in its entirety.

In practice, this would mean one of three things. If the House as a whole is reasonably balanced, blue states would draw fair maps. If the House is skewed in Democrats’ favor (as it was in the 1970s and 1980s), blue states would craft pro-Republican maps. And if the House has a pro-Republican tilt (as over the last decade), blue states would redistrict to benefit Democrats. . . .

Had New York enacted a reform along these lines, its now-defunct congressional map would be valid. Again, that map made the House fairer by helping to offset pro-Republican gerrymanders elsewhere. This idea is potent enough that if just a few more blue states were persuaded, an unbiased House would actually be attained. Notably, California, Colorado, and Washington are all blue states whose independent commissions are barred from considering partisanship. If instead those commissions were instructed to pursue national partisan fairness—for instance, through voter initiatives taking effect later this decade—the commissions are responsible for enough districts that a fair House would, in fact, be the result.