The ruling issued Monday is a major victory for Democrats who have been in the minority for six years and lost ground in this year's election. A three-judge panel tossed maps drawn by Republican lawmakers five years ago, saying they violate the voting rights of Democrats.
The maps divide Wisconsin into 99 Assembly and 32 Senate districts. A dozen voters sued last year, arguing that the boundaries discriminated against Democrats by diluting their voting power.
Attorneys for the state argued that the districts simply reflect that Wisconsin has been trending Republican.
The ruling can be appealed to the U.S. Supreme Court.
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