In a massive victory for Democrats, a federal court hearing a challenge to North Carolina’s Republican-drawn congressional map struck it down on Tuesday evening as a partisan gerrymander designed to benefit the GOP in violation of the constitution. The ramifications of this ruling are enormous: If current district lines are replaced with a nonpartisan map, Democrats could gain anywhere from two to five seats, according to an analysis by Stephen Wolf, as shown at the top of this post.

The case could also give further ammunition to plaintiffs seeking to invalidate gerrymandered maps elsewhere on the same grounds. Republicans will inevitably appeal to the Supreme Court, which is adjudicating two other similar cases, so the outcome may yet change. It’s important to note that the Supreme Court has never before sustained a challenge to a map on the basis that it impermissibly benefits one political party over another, but it recently signaled a new openness toward doing so, so there’s a real chance this ruling could stand. And if new lines are put in place for this year’s midterm elections, that would go a long way toward helping Democrats win back the House.