This is an open question to the attorneys and others involved in challenging North Carolina's legislative and Congressional districts. Why not challenge the foundation of partisan redistricting as violating the fundamental principles of democracy and equality ... not limited to issues of race?
It's my understanding that the legal arguments have been constructed around racial discrimination, relying on historical precedent (which was undermined by the US Supreme Court's ruling on the Voting Rights Act). That's fine as far as it goes, but it doesn't go nearly far enough. As happened in Texas, Republicans in North Carolina have set out to increase their electoral strength through gerrymandering. Yes, it's a long-standing practice of corruption, but that doesn't make it any less despicable.
In 2011, both houses of the Texas Legislature were controlled by large Republican majorities, and their redistricting decisions were designed to increase the Republican Party’s electoral prospects at the expense of the Democrats. It is perfectly constitutional for a Republican-controlled legislature to make partisan districting decisions, even if there are incidental effects on minority voters who support Democratic candidates.
Because of extreme gerrymandering, a Democrat's vote for Congress in North Carolina is worth only 3/5ths of a Republican's vote. There is no place in the universe where that reality can be judged as fair.