A panel of federal judges has struck down two North Carolina majority black congressional districts, saying race was the predominant factor in drawing those lines but state legislators lacked the justification for doing so.The judges ruled late Friday that the 1st and 12th Districts violated the Constitution's equal protection provision and must be redrawn. The judges ordered the General Assembly to come up with new boundaries within two weeks, although the state could seek a delay with an appeals court. Congressional primaries are set for March 15.Republican lawmakers drew the two districts with majority black voting age populations, even though both districts were below 50 percent in the previous round of redistricting and voters had elected black lawmakers.State attorneys argued that race wasn't the predominant motive for forming either district.