The independent council that rejected the map was set up in law by Democrats. If they hadn't passed that law recently (or just undid it), then there would be no legal problem. So it's actually their own check that stopped them.
Similar to how only companies with an ethics hotline get ethics complaints.
The commission was set up on 2014 (this is the first time it's been in place). My point was that the Democrats put the amendment on the ballot in the first place. If they had decided otherwise, it never would have left the state legislature.
They were, in a very real sense, the people who instituted the independent commission. A commission that deadlocked itself before the state legislature decided it failed and they needed to draw the lines.
Had they not voluntarily limited their own power, there would be no legal case at all.
Similar to how only companies with an ethics hotline get ethics complaints.