US Senators John McCain (R-Ariz.) and Sheldon Whitehouse (D-R.I.) are joining the legal fight against partisan gerrymandering.

McCain and Whitehouse filed a joint amicus brief to the Supreme Court in the case, Gill v. Whitford -- the first case in which a federal court ruled electoral districts unconstitutional not on the basis of race, gender, or socioeconomic class, but because of political discrimination.

In this case, the court ruled that Wisconsin legislative districts were so partisan that they violated the voting rights of those outside the Republican Party, the party that currently controls the state legislature and the redistricting process.

Of note, 31 briefs have been filed in Gill v Whitford against extreme partisan gerrymandering.

“Americans do not like gerrymandering,” McCain and Whitehouse write.

“They see its mischief, and absent a legal remedy, their sense of powerlessness and discouragement has increased, deepening the crisis of confidence in our democracy. We share this perspective. From our vantage point, we see wasted votes and silenced voices. We see hidden power. And we see a correctable problem.”

Gill v. Whitford, which is scheduled to be heard on October 3, forces the high court to revisit a 2004 decision in Vieth v. Jubelirer, in which the justices ruled that there was no measurable standard the court could use to determine what constitutes "too partisan" in legislative redistricting.

Without established Supreme Court precedent, federal courts have been reluctant to take up gerrymandering cases that don't deal with racial or socioeconomic discrimination.

"The increase in partisan gerrymandering following Vieth, fueled by dark money contributions and advanced technology, distorts our representative democracy and pollutes Americans’ faith in their political institutions,” McCain and Whitehouse write.

They add, “As Republicans and Democrats battle each other to control redistricting, the real losers are the American people.”

The situation, however, has changed as plaintiffs and redistricting reformers are using statistical models like the efficiency gap to establish a measurable standard to show how extreme partisan gerrymandering has become.

Gill v. Whitford has changed the legal and judicial paradigm, potentially opening the door for future challenges to partisan gerrymandering across the country, and an end to the two-party scheme.

Read McCain and Whitehouse's full amicus brief:

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