The U.S. Capitol (Karen Bleier/AFP/Getty Images)

In 2017, the Supreme Court will take up the issue of partisan gerrymandering. Depending on how the court rules, its decisions could have far-reaching implications for the partisan balance in the U.S. House of Representatives and state legislatures — and for the future of redistricting across the country.

Gerrymandering has helped give the Republican Party a significant advantage in Congress. Because Republicans had unified control of twice as many states as Democrats when the last congressional district maps were drawn, estimates suggest that gerrymandering before the 2012 elections cost Democrats between 20 and 41 seats in the House.

Partisan gerrymandering has become the norm in U.S. politics because the Supreme Court has declined to declare it unconstitutional. For three decades, a majority of justices have failed to identify manageable standards to determine when a plan rises to the level of an unconstitutional partisan gerrymander.

As a result, state legislators have come to believe that they can draw partisan gerrymanders so long as long as they satisfy two criteria: They do not violate one-person, one-vote standards and do not reduce the electoral fortunes of African Americans or other protected racial and ethnic groups. As a result, the 2010 round of redistricting saw partisan gerrymandering run amok in some states.

But change may be coming.

Challenges based on state laws and race

In 2015, the Florida Supreme Court invalidated a Florida congressional map as a partisan gerrymander in League of Women Voters of Florida v. Detzner. Although the court relied on very specific provisions of Florida’s constitution, future state law-based challenges may prove more successful than ones based on the U.S. Constitution.

The methods of inference used in the Florida case may also be adapted to the federal context. They may help the Supreme Court decide on questions such as the standard for determining intent, and the need for burden-shifting to defendants to justify the plan if a clear violation is found. At the remedy phase, they may help determine whether an appropriate remedy involves overturning a whole plan or only particular districts, and about the amount of deference due to a legislature.

Another route to contesting partisan gerrymanders involves challenging majority-minority districts in a plan as unconstitutionally packed with racial minorities. This approach relies on cases going back to Shaw v. Reno (1993), arguing that the districts are unconstitutional if race was the predominant factor determining the way they were drawn. If a jurisdiction can be forced to redraw majority-minority districts in a plan, some elements of a carefully crafted partisan gerrymander might fall apart as neighboring districts are necessarily disrupted in the process.

Last December, the U.S. Supreme Court heard oral argument on two Shaw-type challenges, one from Virginia and one from North Carolina. In both states, a mechanical litmus test was applied without consideration of local circumstances that would affect the ability of African American voters to elect a candidate of choice, such as the willingness of white voters (or Hispanics or other minorities) to support a black candidate — a minimum 55 percent black voting age population in legislative districts in Virginia and a more than 50 percent black voting age population for congressional districts in North Carolina.

These two cases will be decided by the high court in 2017. If the courts are attentive to local circumstances, they may conclude that adding minorities to a district serves no legitimate state purpose, but merely serves to unnecessarily pack the district with minorities (who also happen to be largely Democrats).

A focus on the First Amendment

Perhaps most important, however, is a case from Wisconsin (Whitford v. Gill). In November, a three-judge federal court invalidated that state’s legislative districts in a 2 to 1 decision. The majority wrote:

The plaintiffs have established … that the defendants intended and accomplished an entrenchment of the Republican Party likely to endure for the entire decennial period. … They did so when the legitimate redistricting considerations neither required nor warranted the implementation of such a plan.

Whitford was the first time a federal court has ruled a single-member district plan a partisan gerrymander. When there is an appeal of that decision, it will almost certainly be heard by the Supreme Court and has the potential to be a “game-changer.”

One thing that distinguished Whitford from the many previous unsuccessful challenges was that it was based on a First Amendment freedom of association test rather than a 14th Amendment equal protection test. Other federal courts have also noted this distinction. A three-judge panel in Maryland held last year that even if an equal protection claim failed to generate a cause of action, a First Amendment claim against a specific congressional district required a trial on the merits (Shapiro v. McManus). Regardless of the trial outcome, that case will likely come before the U.S. Supreme Court in 2017.

Emerging ways to judge partisan gerrymandering

Complementing the new First Amendment approaches, there are two other relevant developments. First, recent empirical work suggests that potentially unconstitutional partisan plans are concentrated in no more than a dozen states. That means we can use some very simple screening devices to prevent frivolous lawsuits from wasting the courts’ time.

Second, there are new social science approaches to partisan gerrymandering that the Supreme Court has not previously evaluated. These include complementary ways to measure partisan bias; better ways to determine whether observed bias is due to chance or to “natural” factors having to do with the geographic clustering of groups of voters, and methods to measure the expected durability of the partisan effects of a redistricting plan. The latter two considerations had been largely or entirely missing from the gerrymandering challenges previously heard by the Supreme Court.

The court needs evidence about the durability of a plan’s effects to be sure that partisan advantage is not fleeting, but something that leads to the “continued frustration” of a substantial number of voters who are effectively being “shut out of the political process.” My own work looks to combine these and other factors into a five-pronged test specifying necessary and sufficient conditions for a plan to be an unconstitutional partisan gerrymander. It is intended to provide clear and judicially manageable statistical underpinnings for the criteria set down in Whitford, inspired by the form of the three-pronged test for vote dilution in Thornburg v. Gingles (1986), a test whose judicial manageability has been demonstrated over nearly three decades.

Because recent computer-based partisan gerrymandering has been done very skillfully — mainly by wasting opposition votes in “packed” districts — and because increased partisanship has reduced the likelihood of split ticket voting, the results of most 2010 gerrymanders are unlikely to wear off. That gives Republicans a virtual lock on Congress for the rest of the decade. Moreover, the imbalance in unified control of states grew to a more than 4 to 1 Republican advantage following the 2016 elections, suggesting even more aggressive partisan gerrymandering is ahead of us in 2020 unless the Supreme Court acts.

If, in 2017, the court does not specify a manageable standard for identifying unconstitutional partisan gerrymandering, “partisanship gone wild” will continue indefinitely, leaving us with a never-ending political nightmare: congressional delegations whose partisan balance is frozen into place regardless of changes in the preferences of the voters.

Stopping egregious gerrymandering is not a partisan issue; it benefits Republicans right now, but in the past it has advantaged Democrats. Regardless of which political party gains, the loser is U.S. democracy.

Bernard Grofman is the Jack W. Peltason Chair of Democracy Studies at the University of California, Irvine. He is a specialist on redistricting whose work has been cited in nearly a dozen U.S. Supreme Court cases. Most recently he served as the special master to a federal-district court responsible for the redrawing of the lines of Virginia’s 3rd Congressional District after it had been declared unconstitutional.