http://www.dailykos.com/stories/2016/4/11/1513964/-Major-redistricting-lawsuit-could-spell-the-end-of-unfair-partisan-gerrymanders
"Put more concretely, every time a Republican legislator or member of Congress wins with 55 percent of the vote but a Democrat in the same state wins with 85 percent, far more votes are "wasted" on behalf of the Democrat—exactly what Republican cartographers want, and exactly what they’ve achieved in Wisconsin, where the GOP holds 62 percent of seats in the legislature even though Barack Obama carried the state twice."
