GREENSBORO, N.C. (AP) — A trial has wrapped up in a North Carolina courtroom where election advocacy groups and Democrats asked judges to throw out the state’s congressional districts drawn by Republicans for what they label illegal partisan gerrymandering.

A three-judge panel heard four days of testimony and arguments that ended Thursday. The judges didn’t immediately rule.

The plaintiffs sued GOP legislative leaders, saying boundaries for the 13 districts were so lopsided politically that they violated the constitutional rights of voters in the minority party in each district. The Republicans hold a 10-3 seat advantage.

Lawyers for the Republicans argued the lines were properly drawn in accordance with redistricting rules. The plaintiffs offered a mathematician and a political scientist who testified it was almost impossible to draw that map without partisan goals in mind.