This development is unexpected:

Micah Sims, executive director of Common Cause Pennsylvania, said his organization and the state NAACP are considering filing suit in federal court to challenge the new map imposed by the Pennsylvania Supreme Court this week.

He said it may violate the 1965 Voting Rights Act, which banned obstacles to voting by minorities.

Under Pennsylvania’s former 2011 map, drawn by Republicans, nonwhites make up a majority of residents in two Philadelphia-based congressional districts. In the new map, people of color appear to be the majority in only one district, he said….

A challenge to the map under the Voting Rights Act would require substantial evidence beyond simple demographics, said Michael McDonald, a political science professor at the University of Florida who has served as an expert witness or consultant in multiple redistricting and election lawsuits.

If there is a significant minority community in a geographic area, the Voting Rights Act does not require that the congressional district be drawn to be majority-minority, McDonald said. The law requires that the minority be able to effectively elect the candidate of its choosing.

“It’s going to be difficult to mount the evidence,” McDonald said. “If the evidence is going to fall back to, ‘The district was reduced in African American population,’ that’s not sufficient. You’ve got to establish that the African American community is not effective in electing its candidate of choice.”

That can be complicated, he said. For one thing, the minority community’s preferred candidate can be white, or of another racial or ethnic group…..