Perhaps even bigger (and less understood on its potential ramifications) is the case where Arizona's nonpartisan commission for redistricting after Censuses is being sued by its own state legislature, an earlier version of which created said commission.
It's just Arizona on the surface, but, really, this is Iowa, California and every other state with such a commission. As the New York Times explains in detail, both Anthony Kennedy and Antonin Scalia, at least, seemed determined to take a very narrow view of one sentence in the Constitution about electing Members of Congress to gut such commissions everywhere:
The case, Arizona State Legislature v. Arizona Independent Redistricting Commission, No. 13-1314, will turn on the meaning of a single word: “legislature.” The Constitution says that “the Times, Places and Manner of holding Elections for Senators and Representatives shall be prescribed in each State by the Legislature thereof.”
Gut nonpartisan redistricting commissions, and post-Citizens United Koch money floods states even more than now, in the last election before redistricting, especially if that's a non-presidential election year.
Look at 2010. Obamacare was unpopular, in part because of Dear Leader's lame job of selling both it and his stimulus package. It was an off-term election. The GOP killed Democrats in state legislature and gubernatorial elections, then redistricted like hell.
Where it could.
Eight states, including the three above, have some sort of redistricting structure for both U.S. and state elected positions that is not the state legislature. Swing states Colorado, Missouri, Ohio, and Pennsylvania are among them.
Now is it a bit more clear how big of a deal this could be?