A majority for exactly what, however, is an open question. There are many versions of the theory, from those that make state legislatures all-powerful to less doctrinaire ones that allow state constitutions and state law to dictate some aspects of elections but not others.

If the court chooses any of them, it will end up ruing the day, said Nate Persily, a professor of constitutional law at Stanford University.

“Wouldn’t it be ironic,” he said, “if the Supreme Court, which worried about descending into the political thicket by regulating partisan gerrymanders, nevertheless throws our entire election system into disarray?”