Bob Barnes and Jenna Portnoy for WaPo:

The Supreme Court will take another shot at that in the Virginia case. A panel of federal judges said the commonwealth’s plan veered from partisan gerrymandering aimed at protecting incumbents — for which the Supreme Court has shown a high tolerance — into racial gerrymandering, which the Constitution forbids.

In a sense, said Nathaniel Persily, an election-law expert at Stanford Law School, “the Voting Rights Act is on a collision course with the Constitution.”

The questions for Virginia and other states are, he said, “how much can you think about race in construction of districts, and is the use of race in aid of partisan gerrymandering problematic?”

The line is increasingly elusive, especially across the South, where blacks are presumed to be Democrats and whites are increasingly Republican.