Texas should immediately petition that the United States District Court for the Western District of Texas (San Antonio), dismiss the Just Us Department’s lawsuit as frivolous. Currently it has a 10 Republican appointed judge to 5 Democrat appointed judge balance.
Ironically, that is about the same balance as has the United States Court of Appeals for the Fifth Circuit, which the Just Us Department would have to appeal to if the Western District Court dismissed the case.
From there, an appeal would go to Justice Scalia.
The DOJ filed this action in the Southern District of Texas. Absent some reason to transfer this case to the Western District (I can’t think of any, and given the makeup of the court, the DOJ would most certainly oppose such a move), Texas cannot move to dismiss the action in any court other than the Southern District.