North Carolina legislative districts are back in court again as federal judges must decide whether to accept proposed alterations by their appointed third-party expert.

A three-judge panel scheduled a hearing Friday in Greensboro to listen to why a Stanford University law professor they hired redrew boundaries the way he did. House and Senate districts drawn by Republican legislators have been in courts since 2011.

The same judicial panel previously struck down 28 districts as illegal racial gerrymanders, ultimately leading GOP legislators last summer to retool their maps. But the judges said there seemed to be lingering problems with race and constitutional violations and brought in a special master.

GOP lawyers already have said they expect to appeal to the U.S. Supreme Court if the judicial panel approves the professor's proposal.