As to ruling against a state's voting laws - they're Federal judge-presidents.
Their word is apparently Law, or as King John of Magna Carta fame put it - "The law is in my mouth".
That didn't go over too well with the nobles of England...
The only thing I can think of is an aggressive use of the voting rights act, (which reeks of the postbellum occupation of the southern states imho, and is almost certainly unconstitutional - as are so many extensions of federal power , alas). Otherwise it’s a complete mystery to me tonight anyway, how a federal judge could force a state to amend or violate its voter laws on a topic like this, which has always been a matter of state law. Perhaps a FR-er. who happens to know can help out?