Experts weigh in

Told of the data and what it includes, four experts — Mr. Li; Justin Levitt, a professor at Loyola Law School in Los Angeles; James A. Gardner, a professor at the University at Buffalo School of Law; and Nicholas Stephanopoulos, a professor at the University of Chicago Law School — said the collection of partisanship data itself isn’t unusual or telling, but since the outcome of the mapping heavily favored Republicans, the data suggests an attempt to gerrymander.

“Given a congressional map that appears to seriously lock in members of the Republican Party, it’s a little less benign,” Mr. Levitt said.

Such data are actually required in some states, they said, for a positive purpose: to create competitive or politically neutral maps. That’s not what happened here, they said.

“So you’re left with, I guess, at least two plausible accounts: One is unbelievable incompetence,” Mr. Gardner said. “And the other is … deliberately trying to partisan gerrymander.”

Even before knowing for sure that Pennsylvania lawmakers had the partisanship data, Mr. Stephanopoulos said, he was confident they had it.

“It’s completely unsurprising they would have done it. If you’re trying to draw a gerrymander, if you’re trying to draw a map for partisan advantage, you need to have good partisan data,” Mr. Stephanopoulos said. “This evidence is confirmation they were thinking about partisanship when they were drawing districts.”

In response to the “socalled experts,” Mr. Miskin, the spokesman for Mr. Turzai said: “Clearly, by experts using the term ‘gerrymandering,’ and claiming that it’s gerrymandered, they are biased.”