The only real constraint on the parties at this point is the Voting Rights Act, which Congress last renewed for 25 years in 2006. (President George W. Bush signed that bill—this is, after all, one of the nation’s most important civil rights laws.) Two provisions matter: Section 5, which forces states with a history of segregation to “preclear” their line-drawing plans with the Department of Justice or go to court, and Section 2, which allows the Justice Department (and regular people) to challenge districting plans if they dilute the voting power of racial minorities. In the 1990s, the Voting Rights Act prevented the Democrats from getting too greedy about gerrymandering, because the Justice Department used its power to push for majority-minority districts, which sent many black and Latino lawmakers to Congress, but also left safe seats for Republicans. After the 2010 election, Yale law professor Heather Gerken predicted that the Voting Rights Act would modestly constrain Republicans in this last redistricting cycle, and Persily says that’s about right—it could have gone down even worse for the Democrats if the GOP hadn’t been checked by the directive to protect in some way the power of minority votes. The state that had the attention-grabbing legal battle was Texas, which managed to take population growth that was largely Hispanic and black and create four new congressional districts full of Republican voters. As the plan bounced all over the courts, the map mostly stayed in place for 2012.