As the Supreme Court prepares to hear oral arguments in Gill v. Whitford, the case against partisan gerrymandering, it can be helpful to look back at what led to the congressional district maps we have today.

In October, 2012, FairVote released an analysis of the 2011-2012 redistricting, part of Monopoly Politics 2012, titled "Redistricting 2012: The Worst Congressional Map Ever?"

The analysis highlighted how our hardened partisan voting, winner-take-all voting rules, and a remarkable feat of intentional gerrymandering led to a truly abnormal set of district maps, not only skewing results in favor of one political party, but also helping incumbents of both parties become more secure (and less accountable) in their seats.

The plaintiffs/appellees in Gill v. Whitford are only arguing against aggressive gerrymanders to help one political party win more seats. We agree that such gerrymanders violate the rights of voters.

However, it's worth noting that the incumbent-protecting gerrymanders found in this analysis also strike at the heart of our representative democracy.

The analysis includes a number of fascinating statistics. As just one example, we saw a clear pattern of incumbents in potentially competitive districts being protected by redistricting.

A total of 21 incumbents that won in 2010 by less than 10 percentage points saw their districts become at least 3 points safer. Only 7 such incumbents saw their districts become at least 3 points less safe.

True, 21 seats in a 435-seat body is only an effect at the margins, but in today's political environment, change at the margins can make all the difference.

Read FairVote's 2012 analysis:

Editor's note: This article, written by Drew Penrose, originally published on FairVote's website, and has been modified slightly for publication on IVN.